collab: Add screen selector (#31506)

Instead of selecting a screen to share arbitrarily, we'll now allow user
to select the screen to share. Note that sharing multiple screens at the
time is still not supported (though prolly not too far-fetched).

Related to #4666

![image](https://github.com/user-attachments/assets/1afb664f-3cdb-4e0a-bb29-9d7093d87fa5)

Release Notes:

- Added screen selector dropdown to screen share button

---------

Co-authored-by: Kirill Bulatov <kirill@zed.dev>
Co-authored-by: Cole Miller <cole@zed.dev>

crates/ui/src/components/button/icon_button.rs

@@ -178,7 +178,8 @@ impl VisibleOnHover for IconButton {
 }
 
 impl RenderOnce for IconButton {
-    fn render(self, window: &mut Window, cx: &mut App) -> impl IntoElement {
+    #[allow(refining_impl_trait)]
+    fn render(self, window: &mut Window, cx: &mut App) -> ButtonLike {
         let is_disabled = self.base.disabled;
         let is_selected = self.base.selected;
         let selected_style = self.base.selected_style;