settings: Use a derive macro for refine (#38451)

When we refactored settings to not pass JSON blobs around, we ended up
needing
to write *a lot* of code that just merged things (like json merge used
to do).

Use a derive macro to prevent typos in this logic.

Release Notes:

- N/A

crates/vim_mode_setting/src/vim_mode_setting.rs

@@ -16,16 +16,10 @@ pub fn init(cx: &mut App) {
 pub struct VimModeSetting(pub bool);
 
 impl Settings for VimModeSetting {
-    fn from_defaults(content: &SettingsContent, _cx: &mut App) -> Self {
+    fn from_settings(content: &SettingsContent, _cx: &mut App) -> Self {
         Self(content.vim_mode.unwrap())
     }
 
-    fn refine(&mut self, content: &SettingsContent, _cx: &mut App) {
-        if let Some(vim_mode) = content.vim_mode {
-            self.0 = vim_mode;
-        }
-    }
-
     fn import_from_vscode(_vscode: &settings::VsCodeSettings, _content: &mut SettingsContent) {
         // TODO: could possibly check if any of the `vim.<foo>` keys are set?
     }
@@ -34,15 +28,9 @@ impl Settings for VimModeSetting {
 pub struct HelixModeSetting(pub bool);
 
 impl Settings for HelixModeSetting {
-    fn from_defaults(content: &SettingsContent, _cx: &mut App) -> Self {
+    fn from_settings(content: &SettingsContent, _cx: &mut App) -> Self {
         Self(content.helix_mode.unwrap())
     }
 
-    fn refine(&mut self, content: &SettingsContent, _cx: &mut App) {
-        if let Some(helix_mode) = content.helix_mode {
-            self.0 = helix_mode;
-        }
-    }
-
     fn import_from_vscode(_vscode: &settings::VsCodeSettings, _current: &mut SettingsContent) {}
 }