Support .editorconfig (#19455)

Closes https://github.com/zed-industries/zed/issues/8534
Supersedes https://github.com/zed-industries/zed/pull/16349

Potential concerns:
* we do not follow up to the `/` when looking for `.editorconfig`, only
up to the worktree root.
Seems fine for most of the cases, and the rest should be solved
generically later, as the same issue exists for settings.json
* `fn language` in `AllLanguageSettings` is very hot, called very
frequently during rendering. We accumulate and parse all `.editorconfig`
file contents beforehand, but have to go over globs and match these
against the path given + merge the properties still.
This does not seem to be very bad, but needs more testing and
potentially some extra caching.


Release Notes:

- Added .editorconfig support

---------

Co-authored-by: Ulysse Buonomo <buonomo.ulysse@gmail.com>

crates/supermaven/src/supermaven_completion_provider.rs

@@ -121,7 +121,7 @@ impl InlineCompletionProvider for SupermavenCompletionProvider {
         let file = buffer.file();
         let language = buffer.language_at(cursor_position);
         let settings = all_language_settings(file, cx);
-        settings.inline_completions_enabled(language.as_ref(), file.map(|f| f.path().as_ref()))
+        settings.inline_completions_enabled(language.as_ref(), file.map(|f| f.path().as_ref()), cx)
     }
 
     fn refresh(