wayland: Refactor clipboard implementation (#12405)

Fixes https://github.com/zed-industries/zed/issues/12054

Replaces the `copypasta`/`smithay-clipboard` implementation with a new,
custom one

TODO list:

- [x] Cleanup code
- [x] Remove `smithay-clipboard`
- [x] Add more mime types to the supported list

Release Notes:

- Fixed drag and drop on Gnome
- Fixed clipboard paste on Hyprland

crates/editor/src/editor.rs

@@ -2210,7 +2210,7 @@ impl Editor {
         // Copy selections to primary selection buffer
         #[cfg(target_os = "linux")]
         if local {
-            let selections = self.selections.all::<usize>(cx);
+            let selections = &self.selections.disjoint;
             let buffer_handle = self.buffer.read(cx).read(cx);
 
             let mut text = String::new();