Allow setting XDG application ID on wayland

src/Core.zig

@@ -24,6 +24,9 @@ windows: mach.Objects(
         // TODO: allocation/free strategy
         title: [:0]const u8 = "Mach Window",
 
+        // XDG application ID of the window
+        app_id: [:0]const u8 = "",
+
         /// Texture format of the framebuffer (read-only)
         framebuffer_format: gpu.Texture.Format = .bgra8_unorm,
 

src/core/linux/Wayland.zig

@@ -177,6 +177,7 @@ pub fn initWindow(
     wl = &core_window.native.?.wayland;
 
     c.xdg_toplevel_set_title(wl.toplevel, @ptrCast(core_window.title));
+    c.xdg_toplevel_set_app_id(wl.toplevel, @ptrCast(core_window.app_id));
 
     // Commit changes to surface
     c.wl_surface_commit(wl.surface);