settings ui: Improve setting proc macro and add scroll to UI (#37581)

This PR improves the settings_ui proc macro by taking into account more
serde attributes
1. rename_all
2. rename
3. flatten

We also pass field documentation to the UI layer now too. This allows ui
elements to have more information like the switch field description.

We got the scrollbar working and started getting language settings to
show up.

Release Notes:

- N/A

---------

Co-authored-by: Ben Kunkle <ben@zed.dev>

crates/editor/src/editor_settings.rs

@@ -748,6 +748,7 @@ pub struct ScrollbarAxesContent {
 #[derive(
     Copy, Clone, Debug, Default, Serialize, Deserialize, JsonSchema, PartialEq, Eq, SettingsUi,
 )]
+#[settings_ui(group = "Gutter")]
 pub struct GutterContent {
     /// Whether to show line numbers in the gutter.
     ///