settings_ui: Add UI and buffer font weight controls (#15104)

This PR adds settings controls for the UI and buffer font weight
settings.

It also does some work around grouping the settings into related
sections.

Release Notes:

- N/A

crates/settings_ui/Cargo.toml

@@ -13,10 +13,9 @@ path = "src/settings_ui.rs"
 
 [dependencies]
 command_palette_hooks.workspace = true
+editor.workspace = true
 feature_flags.workspace = true
-fs.workspace = true
 gpui.workspace = true
-project.workspace = true
 settings.workspace = true
 theme.workspace = true
 ui.workspace = true