Fix use_on_type_format setting being unused per language (#18387)

Before this change, `use_on_type_format` would only have an effect when
defined on a global level in our settings.

But our default.json settings would also document that it's used in
language settings, i.e.:

```json
{
  "languages": {
    "C": {
      "use_on_type_format": false
    },
    "C++": {
      "use_on_type_format": false
    }
  }
}
```

But this did **not** work.

With the change, it now works globally and per-language.

Release Notes:

- Fixed `use_on_type_format` setting not working when defined inside
`"languages"` in the settings. This change will now change the default
behavior for C, C++, and Markdown, by turning language server's
`OnTypeFormatting` completions off by default.

Co-authored-by: Bennet <bennet@zed.dev>

crates/editor/src/editor.rs

@@ -3442,7 +3442,7 @@ impl Editor {
                 s.select(new_selections)
             });
 
-            if !bracket_inserted && EditorSettings::get_global(cx).use_on_type_format {
+            if !bracket_inserted {
                 if let Some(on_type_format_task) =
                     this.trigger_on_type_formatting(text.to_string(), cx)
                 {
@@ -4191,6 +4191,15 @@ impl Editor {
             .read(cx)
             .text_anchor_for_position(position, cx)?;
 
+        let settings = language_settings::language_settings(
+            buffer.read(cx).language_at(buffer_position).as_ref(),
+            buffer.read(cx).file(),
+            cx,
+        );
+        if !settings.use_on_type_format {
+            return None;
+        }
+
         // OnTypeFormatting returns a list of edits, no need to pass them between Zed instances,
         // hence we do LSP request & edit on host side only — add formats to host's history.
         let push_to_lsp_host_history = true;