Video: Expose video driver functions

[nickelpro]

Sometimes you want a dummy driver, sometimes you want the offscreen driver, and sometimes on Linux you actually want to make a decision between X11 and Wayland.

This requires exposure of a couple of video driver functions which are unfortunately quite stringy. This exposes those functions and attempts to make them less stringy.

[albin-johansson]

Hi, thanks for working to improve the library. I'll be taking a look at these additions later, I have some other stuff that I'm working on at the moment. But the changes look pretty solid.