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

While `scap` does have support for Wayland and Windows, but haven't seen
screensharing work properly there yet. So for now just adding support
for X11 screensharing.

WIP branches for enabling wayland and windows support:

* https://github.com/zed-industries/zed/tree/wayland-screenshare
* https://github.com/zed-industries/zed/tree/windows-screenshare


Release Notes:

- Added support for screensharing on X11 (Linux)

---------

Co-authored-by: Conrad <conrad@zed.dev>
Co-authored-by: Mikayla <mikayla@zed.dev>
Co-authored-by: Junkui Zhang <364772080@qq.com>

crates/gpui/src/platform/linux/wayland/client.rs

@@ -7,6 +7,7 @@ use std::{
     time::{Duration, Instant},
 };
 
+use anyhow::anyhow;
 use calloop::{
     EventLoop, LoopHandle,
     timer::{TimeoutAction, Timer},
@@ -14,7 +15,7 @@ use calloop::{
 use calloop_wayland_source::WaylandSource;
 use collections::HashMap;
 use filedescriptor::Pipe;
-
+use futures::channel::oneshot;
 use http_client::Url;
 use smallvec::SmallVec;
 use util::ResultExt;
@@ -85,7 +86,8 @@ use crate::{
     FileDropEvent, ForegroundExecutor, KeyDownEvent, KeyUpEvent, Keystroke, LinuxCommon, Modifiers,
     ModifiersChangedEvent, MouseButton, MouseDownEvent, MouseExitEvent, MouseMoveEvent,
     MouseUpEvent, NavigationDirection, Pixels, PlatformDisplay, PlatformInput, Point, SCROLL_LINES,
-    ScaledPixels, ScrollDelta, ScrollWheelEvent, Size, TouchPhase, WindowParams, point, px, size,
+    ScaledPixels, ScreenCaptureSource, ScrollDelta, ScrollWheelEvent, Size, TouchPhase,
+    WindowParams, point, px, size,
 };
 
 /// Used to convert evdev scancode to xkb scancode
@@ -633,6 +635,24 @@ impl LinuxClient for WaylandClient {
         None
     }
 
+    fn is_screen_capture_supported(&self) -> bool {
+        false
+    }
+
+    fn screen_capture_sources(
+        &self,
+    ) -> oneshot::Receiver<anyhow::Result<Vec<Box<dyn ScreenCaptureSource>>>> {
+        // TODO: Get screen capture working on wayland. Be sure to try window resizing as that may
+        // be tricky.
+        //
+        // start_scap_default_target_source()
+        let (sources_tx, sources_rx) = oneshot::channel();
+        sources_tx
+            .send(Err(anyhow!("Wayland screen capture not yet implemented.")))
+            .ok();
+        sources_rx
+    }
+
     fn open_window(
         &self,
         handle: AnyWindowHandle,