klipper: place MIME actions after user configured actions in actions menu

Reason for the change

The user configured actions are likely more important than the MIME actions, since the user specifically added them with custom regexen and commands.

Test plan

Tested manually by adding the patch to the Debian plasma-workspace package, building/installing it, restarting plasmashell and triggering the clipboard actions menu. Everything works the same except that the order is more useful.

Screenshots or screen recordings

Not included because they contain private information on currently configured clipboard actions.

Bugs fixed

None.