Rust 1.78 (#11314)

Notable things I've had to fix due to 1.78:
- Better detection of unused items
- New clippy lint (`assigning_clones`) that points out places where assignment operations with clone rhs could be replaced with more performant `clone_into`
Release Notes:

- N/A

crates/gpui/src/platform/linux/x11/window.rs

@@ -460,10 +460,6 @@ impl PlatformWindow for X11Window {
         Modifiers::default()
     }
 
-    fn as_any_mut(&mut self) -> &mut dyn std::any::Any {
-        self
-    }
-
     fn set_input_handler(&mut self, input_handler: PlatformInputHandler) {
         self.0.state.borrow_mut().input_handler = Some(input_handler);
     }
@@ -587,10 +583,6 @@ impl PlatformWindow for X11Window {
         self.0.callbacks.borrow_mut().resize = Some(callback);
     }
 
-    fn on_fullscreen(&self, callback: Box<dyn FnMut(bool)>) {
-        self.0.callbacks.borrow_mut().fullscreen = Some(callback);
-    }
-
     fn on_moved(&self, callback: Box<dyn FnMut()>) {
         self.0.callbacks.borrow_mut().moved = Some(callback);
     }
@@ -607,11 +599,6 @@ impl PlatformWindow for X11Window {
         self.0.callbacks.borrow_mut().appearance_changed = Some(callback);
     }
 
-    // todo(linux)
-    fn is_topmost_for_position(&self, _position: Point<Pixels>) -> bool {
-        unimplemented!()
-    }
-
     fn draw(&self, scene: &Scene) {
         let mut inner = self.0.state.borrow_mut();
         inner.renderer.draw(scene);