Revert "Remove cx from ThemeSettings (#38836)" (#39691)

This reverts commit a2a7bd139a.

This caused themes to not load correctly on startup, you needed to edit
your settings.

Release Notes:

- N/A

crates/call/src/call_settings.rs

@@ -1,3 +1,4 @@
+use gpui::App;
 use settings::Settings;
 
 #[derive(Debug)]
@@ -7,11 +8,17 @@ pub struct CallSettings {
 }
 
 impl Settings for CallSettings {
-    fn from_settings(content: &settings::SettingsContent) -> Self {
+    fn from_settings(content: &settings::SettingsContent, _cx: &mut App) -> Self {
         let call = content.calls.clone().unwrap();
         CallSettings {
             mute_on_join: call.mute_on_join.unwrap(),
             share_on_join: call.share_on_join.unwrap(),
         }
     }
+
+    fn import_from_vscode(
+        _vscode: &settings::VsCodeSettings,
+        _current: &mut settings::SettingsContent,
+    ) {
+    }
 }