Add support for applying theme after extension is installed (#9529)

Release Notes:

- Added support for opening the theme selector with installed themes
after installing an extension containing themes.
([#9228](https://github.com/zed-industries/zed/issues/9228)).

<img width="1315" alt="Screenshot 2024-03-20 at 11 00 35 AM"
src="https://github.com/zed-industries/zed/assets/1486634/593389b3-eade-4bce-ae17-25c02a074f21">

---------

Co-authored-by: Marshall Bowers <elliott.codes@gmail.com>

crates/zed/src/zed/app_menus.rs

@@ -20,7 +20,7 @@ pub fn app_menus() -> Vec<Menu<'static>> {
                         MenuItem::action("Open Default Settings", super::OpenDefaultSettings),
                         MenuItem::action("Open Default Key Bindings", super::OpenDefaultKeymap),
                         MenuItem::action("Open Local Settings", super::OpenLocalSettings),
-                        MenuItem::action("Select Theme...", theme_selector::Toggle),
+                        MenuItem::action("Select Theme...", theme_selector::Toggle::default()),
                     ],
                 }),
                 MenuItem::action("Extensions", extensions_ui::Extensions),