chore: Clippy fixes for 1.80 (#13987)

The biggest hurdle turned out to be use of `Arc<Language>` in maps, as
`clippy::mutable_key_type` started triggering on it (due to - I suppose
- internal mutability on `HighlightMap`?). I switched over to using
`LanguageId` as the key type in some of the callsites, as that's what
`Language` uses anyways for it's hash/eq, though I've still had to
suppress the lint outside of language crate.

/cc @maxdeviant , le clippy guru.

Release Notes:

- N/A

crates/editor/src/editor.rs

@@ -11093,6 +11093,7 @@ impl Editor {
                 if *singleton_buffer_edited {
                     if let Some(project) = &self.project {
                         let project = project.read(cx);
+                        #[allow(clippy::mutable_key_type)]
                         let languages_affected = multibuffer
                             .read(cx)
                             .all_buffers()