Wayland: Release pressed events on application focus out

Looks like I always assumed wrongly that the compositor would send us
key release events when unfocusing... It did not.

platform/linuxbsd/wayland/display_server_wayland.cpp

@@ -1174,6 +1174,7 @@ void DisplayServerWayland::process_events() {
 				if (OS::get_singleton()->get_main_loop()) {
 					OS::get_singleton()->get_main_loop()->notification(MainLoop::NOTIFICATION_APPLICATION_FOCUS_OUT);
 				}
+				Input::get_singleton()->release_pressed_events();
 			}
 		}