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_host/src/extension_host.rs

@@ -162,6 +162,7 @@ pub struct ExtensionIndexLanguageEntry {
     pub extension: Arc<str>,
     pub path: PathBuf,
     pub matcher: LanguageMatcher,
+    pub hidden: bool,
     pub grammar: Option<Arc<str>>,
 }
 
@@ -1097,6 +1098,7 @@ impl ExtensionStore {
                 language_name.clone(),
                 language.grammar.clone(),
                 language.matcher.clone(),
+                language.hidden,
                 Arc::new(move || {
                     let config = std::fs::read_to_string(language_path.join("config.toml"))?;
                     let config: LanguageConfig = ::toml::from_str(&config)?;
@@ -1324,6 +1326,7 @@ impl ExtensionStore {
                         extension: extension_id.clone(),
                         path: relative_path,
                         matcher: config.matcher,
+                        hidden: config.hidden,
                         grammar: config.grammar,
                     },
                 );