Reapply support for X11 screenshare (#28160)

Reapplies #27807 after [revert due to not building on
ARM](https://github.com/zed-industries/zed/pull/28141) by updating scap
to include [a fix to its build on
ARM](08f0a01417)

Release Notes:

- N/A

---------

Co-authored-by: Marshall Bowers <git@maxdeviant.com>

crates/title_bar/src/collab.rs

@@ -299,10 +299,7 @@ impl TitleBar {
         let is_screen_sharing = room.is_screen_sharing();
         let can_use_microphone = room.can_use_microphone();
         let can_share_projects = room.can_share_projects();
-        let screen_sharing_supported = match self.platform_style {
-            PlatformStyle::Mac => true,
-            PlatformStyle::Linux | PlatformStyle::Windows => false,
-        };
+        let screen_sharing_supported = cx.is_screen_capture_supported();
 
         let mut children = Vec::new();