feat(fmt): support CSS, SCSS, Sass and Less (#24870)

This PR integrates [Malva](https://github.com/g-plane/malva) into `deno
fmt`, which introduces the ability to format CSS, SCSS, Sass and Less
files.

On Linux x64 6.10, this PR increases about 800KiB:

```                                                                                                                                                                      
❯ wc -c target/release/deno
125168728 target/release/deno

❯ wc -c target/release/deno
124349456 target/release/deno
```

2 files changed, 29 insertions, 3 deletions

diff --git a/cli/args/flags.rs b/cli/args/flags.rs
index e28ce549b..acdcaf8a7 100644
--- a/cli/args/flags.rs
+++ b/cli/args/flags.rs
@@ -200,6 +200,7 @@ pub struct FmtFlags {
   pub prose_wrap: Option<String>,
   pub no_semicolons: Option<bool>,
   pub watch: Option<WatchFlags>,
+  pub unstable_css: bool,
   pub unstable_yaml: bool,
 }
 
@@ -2018,8 +2019,8 @@ Ignore formatting a file by adding an ignore comment at the top of the file:
             // prefer using ts for formatting instead of js because ts works in more scenarios
             .default_value("ts")
             .value_parser([
-              "ts", "tsx", "js", "jsx", "md", "json", "jsonc", "yml", "yaml",
-              "ipynb",
+              "ts", "tsx", "js", "jsx", "md", "json", "jsonc", "css", "scss",
+              "sass", "less", "yml", "yaml", "ipynb",
             ]),
         )
         .arg(
@@ -2097,6 +2098,13 @@ Ignore formatting a file by adding an ignore comment at the top of the file:
             ),
         )
         .arg(
+          Arg::new("unstable-css")
+            .long("unstable-css")
+            .help("Enable formatting CSS, SCSS, Sass and Less files.")
+            .value_parser(FalseyValueParser::new())
+            .action(ArgAction::SetTrue),
+        )
+        .arg(
           Arg::new("unstable-yaml")
             .long("unstable-yaml")
             .help("Enable formatting YAML files.")
@@ -4163,6 +4171,7 @@ fn fmt_parse(flags: &mut Flags, matches: &mut ArgMatches) {
   let single_quote = matches.remove_one::<bool>("single-quote");
   let prose_wrap = matches.remove_one::<String>("prose-wrap");
   let no_semicolons = matches.remove_one::<bool>("no-semicolons");
+  let unstable_css = matches.get_flag("unstable-css");
   let unstable_yaml = matches.get_flag("unstable-yaml");
 
   flags.subcommand = DenoSubcommand::Fmt(FmtFlags {
@@ -4175,6 +4184,7 @@ fn fmt_parse(flags: &mut Flags, matches: &mut ArgMatches) {
     prose_wrap,
     no_semicolons,
     watch: watch_arg_parse(matches),
+    unstable_css,
     unstable_yaml,
   });
 }
@@ -5881,6 +5891,7 @@ mod tests {
           single_quote: None,
           prose_wrap: None,
           no_semicolons: None,
+          unstable_css: false,
           unstable_yaml: false,
           watch: Default::default(),
         }),
@@ -5905,6 +5916,7 @@ mod tests {
           single_quote: None,
           prose_wrap: None,
           no_semicolons: None,
+          unstable_css: false,
           unstable_yaml: false,
           watch: Default::default(),
         }),
@@ -5929,6 +5941,7 @@ mod tests {
           single_quote: None,
           prose_wrap: None,
           no_semicolons: None,
+          unstable_css: false,
           unstable_yaml: false,
           watch: Default::default(),
         }),
@@ -5953,6 +5966,7 @@ mod tests {
           single_quote: None,
           prose_wrap: None,
           no_semicolons: None,
+          unstable_css: false,
           unstable_yaml: false,
           watch: Some(Default::default()),
         }),
@@ -5966,6 +5980,7 @@ mod tests {
       "fmt",
       "--watch",
       "--no-clear-screen",
+      "--unstable-css",
       "--unstable-yaml"
     ]);
     assert_eq!(
@@ -5983,6 +5998,7 @@ mod tests {
           single_quote: None,
           prose_wrap: None,
           no_semicolons: None,
+          unstable_css: true,
           unstable_yaml: true,
           watch: Some(WatchFlags {
             hmr: false,
@@ -6018,6 +6034,7 @@ mod tests {
           single_quote: None,
           prose_wrap: None,
           no_semicolons: None,
+          unstable_css: false,
           unstable_yaml: false,
           watch: Some(Default::default()),
         }),
@@ -6042,6 +6059,7 @@ mod tests {
           single_quote: None,
           prose_wrap: None,
           no_semicolons: None,
+          unstable_css: false,
           unstable_yaml: false,
           watch: Default::default(),
         }),
@@ -6074,6 +6092,7 @@ mod tests {
           single_quote: None,
           prose_wrap: None,
           no_semicolons: None,
+          unstable_css: false,
           unstable_yaml: false,
           watch: Some(Default::default()),
         }),
@@ -6111,6 +6130,7 @@ mod tests {
           single_quote: Some(true),
           prose_wrap: Some("never".to_string()),
           no_semicolons: Some(true),
+          unstable_css: false,
           unstable_yaml: false,
           watch: Default::default(),
         }),
@@ -6142,6 +6162,7 @@ mod tests {
           single_quote: Some(false),
           prose_wrap: None,
           no_semicolons: Some(false),
+          unstable_css: false,
           unstable_yaml: false,
           watch: Default::default(),
         }),
diff --git a/cli/args/mod.rs b/cli/args/mod.rs
index bd49c0c15..afad0528c 100644
--- a/cli/args/mod.rs
+++ b/cli/args/mod.rs
@@ -281,6 +281,7 @@ impl BenchOptions {
 
 #[derive(Clone, Debug, Default, PartialEq, Eq, Hash)]
 pub struct UnstableFmtOptions {
+  pub css: bool,
   pub yaml: bool,
 }
 
@@ -314,6 +315,7 @@ impl FmtOptions {
     Self {
       options: resolve_fmt_options(fmt_flags, fmt_config.options),
       unstable: UnstableFmtOptions {
+        css: unstable.css || fmt_flags.unstable_css,
         yaml: unstable.yaml || fmt_flags.unstable_yaml,
       },
       files: fmt_config.files,
@@ -1330,8 +1332,10 @@ impl CliOptions {
   }
 
   pub fn resolve_config_unstable_fmt_options(&self) -> UnstableFmtOptions {
+    let workspace = self.workspace();
     UnstableFmtOptions {
-      yaml: self.workspace().has_unstable("fmt-yaml"),
+      css: workspace.has_unstable("fmt-css"),
+      yaml: workspace.has_unstable("fmt-yaml"),
     }
   }
 
@@ -1664,6 +1668,7 @@ impl CliOptions {
         "sloppy-imports",
         "byonm",
         "bare-node-builtins",
+        "fmt-css",
         "fmt-yaml",
       ]);
       // add more unstable flags to the same vector holding granular flags