Feature: Center floating windows

Yabai has a command to move floating windows to the center of your screen, for a certain size. 

My ideal would to float a window in the center, for a certain percentage of the viewport (w 80%, h 70%, maybe with max w and max h, because of wide screens).

I also like it to be macos center, that means it's a little higher then dead center, somehow that feels more natural (saw that in the loop wm).

