languages: Remove a eager conversion from LanguageName to String (#35667)

This PR changes the signature of `language_names` from

```rust
pub fn language_names(&self) -> Vec<String>
// Into
pub fn language_names(&self) -> Vec<LanguageName>
```

The function previously eagerly converted `LanguageName`'s to
`String`'s, which requires the reallocation of all of the elements. The
functions get called in many places in the code base, but only one of
which actually requires the conversion to a `String`. In one case it
would do a `SharedString` -> `String` -> `SharedString` conversion,
which is now totally bypassed.

Release Notes:

- N/A

crates/language/src/language.rs

@@ -2353,9 +2353,9 @@ mod tests {
         assert_eq!(
             languages.language_names(),
             &[
-                "JSON".to_string(),
-                "Plain Text".to_string(),
-                "Rust".to_string(),
+                LanguageName::new("JSON"),
+                LanguageName::new("Plain Text"),
+                LanguageName::new("Rust"),
             ]
         );
 
@@ -2366,9 +2366,9 @@ mod tests {
         assert_eq!(
             languages.language_names(),
             &[
-                "JSON".to_string(),
-                "Plain Text".to_string(),
-                "Rust".to_string(),
+                LanguageName::new("JSON"),
+                LanguageName::new("Plain Text"),
+                LanguageName::new("Rust"),
             ]
         );
 
@@ -2379,9 +2379,9 @@ mod tests {
         assert_eq!(
             languages.language_names(),
             &[
-                "JSON".to_string(),
-                "Plain Text".to_string(),
-                "Rust".to_string(),
+                LanguageName::new("JSON"),
+                LanguageName::new("Plain Text"),
+                LanguageName::new("Rust"),
             ]
         );
 

crates/language/src/language_registry.rs

@@ -547,15 +547,15 @@ impl LanguageRegistry {
         self.state.read().language_settings.clone()
     }
 
-    pub fn language_names(&self) -> Vec<String> {
+    pub fn language_names(&self) -> Vec<LanguageName> {
         let state = self.state.read();
         let mut result = state
             .available_languages
             .iter()
-            .filter_map(|l| l.loaded.not().then_some(l.name.to_string()))
-            .chain(state.languages.iter().map(|l| l.config.name.to_string()))
+            .filter_map(|l| l.loaded.not().then_some(l.name.clone()))
+            .chain(state.languages.iter().map(|l| l.config.name.clone()))
             .collect::<Vec<_>>();
-        result.sort_unstable_by_key(|language_name| language_name.to_lowercase());
+        result.sort_unstable_by_key(|language_name| language_name.as_ref().to_lowercase());
         result
     }