Notifications: Sort the settings appropriately in the FM (#7734)

Otherwise it's flagged as orphaned ;).

(Also tweak indenting of said settings to be more in line with how we
usually do these).

Overlooked in #7718

frontend/ui/elements/filemanager_menu_order.lua

@@ -84,6 +84,8 @@ local order = {
         "----------------------------",
         "screen_timeout",
         "fullscreen",
+        "----------------------------",
+        "screen_notification",
     },
     taps_and_gestures = {
         "gesture_manager",