Introduce a new ToggleGraphicsProfiler command (#7607)

On macOS, this will enable or disable the Metal HUD at runtime. Note
that this only works when Zed is bundled because it requires to set the
`MetalHudEnabled` key in the Info.plist.

Release Notes:

- Added a new `ToggleGraphicsProfiler` command that can be used as an
action (or via the `Help -> Toggle Graphics Profiler` menu) to
investigate graphics performance.

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

@@ -428,4 +428,8 @@ impl PlatformWindow for LinuxWindow {
         let inner = self.0.inner.lock();
         inner.renderer.atlas().clone()
     }
+
+    fn set_graphics_profiler_enabled(&self, enabled: bool) {
+        todo!("linux")
+    }
 }