Add an option to disable wm compositor when having fullscreen windows

Submitted by Luca osvaldo

Assigned to Olivier Fourdan @olivier

Link to original bug (#12606)

Description

Currently, every desktop environment got an option that disables the desktop effects when they're running a fullscreen window, such as OpenGL games, for improving noticeably the performance.

This is very useful for gamers, and switching manually the compositor off every time isn't a great idea especially for newbies. Xfwm4 improved a lot in all those years, and that little feature will make it the best multi-purpose window manager since it's light and is also can offer tear-free compositing but that's imo a annoying problem. Compiz has this, like marco, muffin and mutter.