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/title_bar/src/collab.rs

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