Add separate JSONC language (#12655)

Resolves https://github.com/zed-industries/extensions/issues/860 and
https://github.com/zed-industries/zed/issues/10921, also
https://github.com/biomejs/biome-zed/issues/11.

### Problem:
When opening .json files, zed allows comments by default in the JSON
language, which can cause some problems.
For example, language-servers also get "json" as the language, which may
show errors for those comments.

<img width="935" alt="image"
src="https://github.com/zed-industries/zed/assets/10381895/fed3d83d-abc0-44b5-9982-eb249bb04c3b">

### Solution:

This PR adds a JSONC language. 

<img width="816" alt="image"
src="https://github.com/zed-industries/zed/assets/10381895/8b40e671-d4f0-4e8d-80cb-82ee7c0ec490">

This allows for more specific configuration for language servers. 
Also any json file can be set explicitly to be JSONC using the
file_types setting:

```jsonc
{
  "file_types": {
    // set all .json files to be seen as JSONC
    "JSONC": ["*.json"]
  }
}
```


Release Notes:

- N/A

assets/settings/default.json

@@ -688,7 +688,9 @@
   //   "TOML": ["Embargo.lock"]
   // }
   //
-  "file_types": {},
+  "file_types": {
+    "JSONC": ["**/.zed/**/*.json", "**/zed/**/*.json"]
+  },
   // The extensions that Zed should automatically install on startup.
   //
   // If you don't want any of these extensions, add this field to your settings