Fix menu

On the defeat/victory screen (at least in the campaign), when you press the ESC button and call up the menu for loading (saving, etc.), bring this menu to the foreground (to the top).

Here's what they're referring to -- if you get the "Defeated" popup, hit escape, then hit "Restart" while the "Defeat" popup is on top of the escape menu, it will exit the match instead of restarting.

Since the exit menu was launched after the "Defeated" popup, it should be displayed on top of the popup and hitting "Restart" should restart the match.

https://github.com/ZeroK-RTS/Zero-K/commit/f71fecd02ab7ca60fc520b7707c54f6b2aeec12c