Add language icons to the language selector (#21298)

Closes https://github.com/zed-industries/zed/issues/21290

This is a first attempt to show the language icons to the selector.
Ideally, I wouldn't like to have yet another place mapping extensions to
icons, as we already have the `file_types.json` file doing that, but I'm
not so sure how to pull from it yet. Maybe in a future pass we'll
improve this and make it more solid.

<img width="700" alt="Screenshot 2024-11-28 at 16 10 27"
src="https://github.com/user-attachments/assets/683c3bef-5389-470f-a41e-3d510b927b61">

Release Notes:

- N/A

---------

Co-authored-by: Kirill Bulatov <kirill@zed.dev>
Co-authored-by: Piotr Osiewicz <24362066+osiewicz@users.noreply.github.com>

crates/extension/src/extension_host_proxy.rs

@@ -159,6 +159,7 @@ pub trait ExtensionLanguageProxy: Send + Sync + 'static {
         language: LanguageName,
         grammar: Option<Arc<str>>,
         matcher: LanguageMatcher,
+        hidden: bool,
         load: Arc<dyn Fn() -> Result<LoadedLanguage> + Send + Sync + 'static>,
     );
 
@@ -175,13 +176,14 @@ impl ExtensionLanguageProxy for ExtensionHostProxy {
         language: LanguageName,
         grammar: Option<Arc<str>>,
         matcher: LanguageMatcher,
+        hidden: bool,
         load: Arc<dyn Fn() -> Result<LoadedLanguage> + Send + Sync + 'static>,
     ) {
         let Some(proxy) = self.language_proxy.read().clone() else {
             return;
         };
 
-        proxy.register_language(language, grammar, matcher, load)
+        proxy.register_language(language, grammar, matcher, hidden, load)
     }
 
     fn remove_languages(