CI/AppImage: Disable Wayland by default

Set I_WANT_A_BROKEN_WAYLAND_UI=1 if you must use it.
But there's gonna be broken stuff.

scripts/appimage/apprun-hooks/default-to-x11.sh

@@ -0,0 +1,9 @@
+if [[ -z "$I_WANT_A_BROKEN_WAYLAND_UI" ]]; then
+	echo "Forcing X11 instead of Wayland, due to various protocol limitations"
+        echo "and Qt issues. If you want to use Wayland, launch DuckStation with"
+	echo "I_WANT_A_BROKEN_WAYLAND_UI=YES set."
+	export QT_QPA_PLATFORM=xcb
+else
+	echo "Wayland is not being disabled. Do not complain when things break."
+fi
+