Revert "Use scap library to implement screensharing on X11 (#27807)" (#28141)

This reverts commit c2afc2271b.

Build on ARM if failing, likely because `c_char` is `u8` on arm and `i8`
on x86:

```
error[E0308]: mismatched types
   --> /home/runner/.cargo/git/checkouts/scap-40ad33e1dd47aaea/5715067/src/targets/linux/mod.rs:75:74
    |
75  |     let result = unsafe { XmbTextPropertyToTextList(display, &mut xname, &mut list, &mut count) };
    |                           -------------------------                      ^^^^^^^^^ expected `*mut *mut *mut u8`, found `&mut *mut *mut i8`
    |                           |
    |                           arguments to this function are incorrect
    |
    = note:    expected raw pointer `*mut *mut *mut u8`
            found mutable reference `&mut *mut *mut i8`
note: function defined here
   --> /home/runner/.cargo/registry/src/index.crates.io-1949cf8c6b5b557f/x11-2.21.0/src/xlib.rs:552:10
    |
552 |   pub fn XmbTextPropertyToTextList (_4: *mut Display, _3: *const XTextProperty, _2: *mut *mut *mut c_char, _1: *mut c_int) -> c_int,
    |          ^^^^^^^^^^^^^^^^^^^^^^^^^
```

Release Notes:

- N/A

crates/workspace/src/workspace.rs

@@ -4423,6 +4423,18 @@ impl Workspace {
         None
     }
 
+    #[cfg(target_os = "windows")]
+    fn shared_screen_for_peer(
+        &self,
+        _peer_id: PeerId,
+        _pane: &Entity<Pane>,
+        _window: &mut Window,
+        _cx: &mut App,
+    ) -> Option<Entity<SharedScreen>> {
+        None
+    }
+
+    #[cfg(not(target_os = "windows"))]
     fn shared_screen_for_peer(
         &self,
         peer_id: PeerId,