feat(task): Task description in the form of comments (#23101)

Closes #22786.

TLDR;
```jsonc
{
  "tasks": {
    // Some comment
    //
    // describing what the task does
    "dev": "deno run -A --watch main.ts"
  }
}
```
```bash
deno task
```
![Screenshot 2024-03-27 at 1 43
49 PM](https://github.com/denoland/deno/assets/17734409/7a14da8c-8e63-45ba-9bfb-590d250b56a9)

7 files changed, 73 insertions, 16 deletions

diff --git a/cli/Cargo.toml b/cli/Cargo.toml
index 12a45aa43..5345f45cf 100644
--- a/cli/Cargo.toml
+++ b/cli/Cargo.toml
@@ -64,7 +64,7 @@ winres.workspace = true
 [dependencies]
 deno_ast = { workspace = true, features = ["bundler", "cjs", "codegen", "proposal", "react", "sourcemap", "transforms", "typescript", "view", "visit"] }
 deno_cache_dir = { workspace = true }
-deno_config = "=0.14.1"
+deno_config = "=0.15.0"
 deno_core = { workspace = true, features = ["include_js_files_for_snapshotting"] }
 deno_doc = { version = "=0.113.1", features = ["html"] }
 deno_emit = "=0.38.2"
diff --git a/cli/args/mod.rs b/cli/args/mod.rs
index 330b10d0f..76de434fd 100644
--- a/cli/args/mod.rs
+++ b/cli/args/mod.rs
@@ -796,11 +796,18 @@ impl CliOptions {
       } else {
         None
       };
+    let parse_options = deno_config::ParseOptions {
+      include_task_comments: matches!(
+        flags.subcommand,
+        DenoSubcommand::Task(..)
+      ),
+    };
     let maybe_config_file = ConfigFile::discover(
       &flags.config_flag,
       flags.config_path_args(&initial_cwd),
       &initial_cwd,
       additional_config_file_names,
+      &parse_options,
     )?;
 
     let mut maybe_package_json = None;
@@ -1183,7 +1190,7 @@ impl CliOptions {
 
   pub fn resolve_tasks_config(
     &self,
-  ) -> Result<IndexMap<String, String>, AnyError> {
+  ) -> Result<IndexMap<String, deno_config::Task>, AnyError> {
     if let Some(config_file) = &self.maybe_config_file {
       config_file.resolve_tasks_config()
     } else if self.maybe_package_json.is_some() {
@@ -1850,7 +1857,12 @@ mod test {
     let cwd = &std::env::current_dir().unwrap();
     let config_specifier =
       ModuleSpecifier::parse("file:///deno/deno.jsonc").unwrap();
-    let config_file = ConfigFile::new(config_text, config_specifier).unwrap();
+    let config_file = ConfigFile::new(
+      config_text,
+      config_specifier,
+      &deno_config::ParseOptions::default(),
+    )
+    .unwrap();
     let actual = resolve_import_map_specifier(
       Some("import-map.json"),
       Some(&config_file),
@@ -1869,7 +1881,12 @@ mod test {
     let config_text = r#"{}"#;
     let config_specifier =
       ModuleSpecifier::parse("file:///deno/deno.jsonc").unwrap();
-    let config_file = ConfigFile::new(config_text, config_specifier).unwrap();
+    let config_file = ConfigFile::new(
+      config_text,
+      config_specifier,
+      &deno_config::ParseOptions::default(),
+    )
+    .unwrap();
     let actual = resolve_import_map_specifier(
       None,
       Some(&config_file),
diff --git a/cli/lsp/config.rs b/cli/lsp/config.rs
index 5fa2a00a6..304a53b8b 100644
--- a/cli/lsp/config.rs
+++ b/cli/lsp/config.rs
@@ -1136,7 +1136,10 @@ impl ConfigData {
     file_fetcher: Option<&FileFetcher>,
   ) -> Self {
     if let Some(specifier) = config_file_specifier {
-      match ConfigFile::from_specifier(specifier.clone()) {
+      match ConfigFile::from_specifier(
+        specifier.clone(),
+        &deno_config::ParseOptions::default(),
+      ) {
         Ok(config_file) => {
           lsp_log!(
             "  Resolved Deno configuration file: \"{}\"",
@@ -1949,7 +1952,12 @@ mod tests {
     config
       .tree
       .inject_config_file(
-        ConfigFile::new("{}", root_uri.join("deno.json").unwrap()).unwrap(),
+        ConfigFile::new(
+          "{}",
+          root_uri.join("deno.json").unwrap(),
+          &deno_config::ParseOptions::default(),
+        )
+        .unwrap(),
       )
       .await;
     assert!(config.specifier_enabled(&root_uri));
@@ -1996,6 +2004,7 @@ mod tests {
           })
           .to_string(),
           root_uri.join("deno.json").unwrap(),
+          &deno_config::ParseOptions::default(),
         )
         .unwrap(),
       )
@@ -2021,6 +2030,7 @@ mod tests {
           })
           .to_string(),
           root_uri.join("deno.json").unwrap(),
+          &deno_config::ParseOptions::default(),
         )
         .unwrap(),
       )
@@ -2038,6 +2048,7 @@ mod tests {
           })
           .to_string(),
           root_uri.join("deno.json").unwrap(),
+          &deno_config::ParseOptions::default(),
         )
         .unwrap(),
       )
@@ -2067,6 +2078,7 @@ mod tests {
           })
           .to_string(),
           root_uri.join("deno.json").unwrap(),
+          &deno_config::ParseOptions::default(),
         )
         .unwrap(),
       )
diff --git a/cli/lsp/diagnostics.rs b/cli/lsp/diagnostics.rs
index 03d962741..e518f4c6e 100644
--- a/cli/lsp/diagnostics.rs
+++ b/cli/lsp/diagnostics.rs
@@ -1617,7 +1617,12 @@ mod tests {
     let config = Config::new_with_roots([resolve_url("file:///").unwrap()]);
     if let Some((base_url, json_string)) = maybe_import_map {
       let base_url = resolve_url(base_url).unwrap();
-      let config_file = ConfigFile::new(json_string, base_url).unwrap();
+      let config_file = ConfigFile::new(
+        json_string,
+        base_url,
+        &deno_config::ParseOptions::default(),
+      )
+      .unwrap();
       config.tree.inject_config_file(config_file).await;
     }
     StateSnapshot {
diff --git a/cli/lsp/documents.rs b/cli/lsp/documents.rs
index 7d1d89b8d..8feeab8de 100644
--- a/cli/lsp/documents.rs
+++ b/cli/lsp/documents.rs
@@ -1886,6 +1886,7 @@ console.log(b, "hello deno");
             })
             .to_string(),
             config.root_uri().unwrap().join("deno.json").unwrap(),
+            &deno_config::ParseOptions::default(),
           )
           .unwrap(),
         )
@@ -1926,6 +1927,7 @@ console.log(b, "hello deno");
             })
             .to_string(),
             config.root_uri().unwrap().join("deno.json").unwrap(),
+            &deno_config::ParseOptions::default(),
           )
           .unwrap(),
         )
diff --git a/cli/lsp/tsc.rs b/cli/lsp/tsc.rs
index 691f7c91d..63c08331d 100644
--- a/cli/lsp/tsc.rs
+++ b/cli/lsp/tsc.rs
@@ -4711,6 +4711,7 @@ mod tests {
           })
           .to_string(),
           resolve_url("file:///deno.json").unwrap(),
+          &deno_config::ParseOptions::default(),
         )
         .unwrap(),
       )
diff --git a/cli/tools/task.rs b/cli/tools/task.rs
index 8f500df34..5eefda73f 100644
--- a/cli/tools/task.rs
+++ b/cli/tools/task.rs
@@ -49,7 +49,13 @@ pub async fn execute_script(
     }
   };
 
-  if let Some(script) = tasks_config.get(task_name) {
+  if let Some(
+    deno_config::Task::Definition(script)
+    | deno_config::Task::Commented {
+      definition: script, ..
+    },
+  ) = tasks_config.get(task_name)
+  {
     let config_file_url = cli_options.maybe_config_file_specifier().unwrap();
     let config_file_path = if config_file_url.scheme() == "file" {
       config_file_url.to_file_path().unwrap()
@@ -222,18 +228,22 @@ fn collect_env_vars() -> HashMap<String, String> {
 
 fn print_available_tasks(
   // order can be important, so these use an index map
-  tasks_config: &IndexMap<String, String>,
+  tasks_config: &IndexMap<String, deno_config::Task>,
   package_json_scripts: &IndexMap<String, String>,
 ) {
   eprintln!("{}", colors::green("Available tasks:"));
 
   let mut had_task = false;
-  for (is_deno, (key, value)) in tasks_config.iter().map(|e| (true, e)).chain(
-    package_json_scripts
-      .iter()
-      .filter(|(key, _)| !tasks_config.contains_key(*key))
-      .map(|e| (false, e)),
-  ) {
+  for (is_deno, (key, task)) in tasks_config
+    .iter()
+    .map(|(k, t)| (true, (k, t.clone())))
+    .chain(
+      package_json_scripts
+        .iter()
+        .filter(|(key, _)| !tasks_config.contains_key(*key))
+        .map(|(k, v)| (false, (k, deno_config::Task::Definition(v.clone())))),
+    )
+  {
     eprintln!(
       "- {}{}",
       colors::cyan(key),
@@ -243,7 +253,17 @@ fn print_available_tasks(
         format!(" {}", colors::italic_gray("(package.json)"))
       }
     );
-    eprintln!("    {value}");
+    let definition = match &task {
+      deno_config::Task::Definition(definition) => definition,
+      deno_config::Task::Commented { definition, .. } => definition,
+    };
+    if let deno_config::Task::Commented { comments, .. } = &task {
+      let slash_slash = colors::italic_gray("//");
+      for comment in comments {
+        eprintln!("    {slash_slash} {}", colors::italic_gray(comment));
+      }
+    }
+    eprintln!("    {definition}");
     had_task = true;
   }
   if !had_task {