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)

1 files changed, 6 insertions, 0 deletions

diff --git a/tests/specs/task/doc_comments_no_args/__test__.jsonc b/tests/specs/task/doc_comments_no_args/__test__.jsonc
new file mode 100644
index 000000000..2f9db088a
--- /dev/null
+++ b/tests/specs/task/doc_comments_no_args/__test__.jsonc
@@ -0,0 +1,6 @@
+{
+  "args": "task",
+  "envs": { "NO_COLOR": "1" },
+  "output": "task.out",
+  "exitCode": 1
+}