Extract Vue extension (#10486)

This PR extracts Vue support into an extension and removes the built-in
C# support from Zed.

Release Notes:

- Removed built-in support for Vue, in favor of making it available as
an extension. The Vue extension will be suggested for download when you
open a `.vue` file.

---------

Co-authored-by: Max <max@zed.dev>

crates/extension/src/extension_manifest.rs

@@ -106,6 +106,8 @@ pub struct LanguageServerManifestEntry {
     languages: Vec<Arc<str>>,
     #[serde(default)]
     pub language_ids: HashMap<String, String>,
+    #[serde(default)]
+    pub code_action_kinds: Option<Vec<lsp::CodeActionKind>>,
 }
 
 impl LanguageServerManifestEntry {