Option to limit FPS at main menu

Main menu makes my GPU usage peg 100%.

For those AFK'ing at the main menu, it is unnecessary to be sitting there at 144 FPS and maxing out our GPU's.

Another thread referencing this issue: https://www.reddit.com/r/PUBATTLEGROUNDS/comments/674j1p/gpu_at_100_only_on_lobby_screen/?st=j418g69e&sh=febc0cff