Hardware accelerated video decoding

[KKhanhH]

Adds hardware accelerated video decoding on the FFmpeg Video Player

[KKhanhH]

This still requires copying hardware frames from gpu memory into cpu memory and then resubmitting as a texture through the renderer.

Might be able to pass hardware buffer directly but would require platform specific code and probably more effort than its worth.
https://stackoverflow.com/questions/57242800/how-to-convert-an-ffmpeg-texture-to-open-gl-texture-without-copying-to-cpu-memor

[KKhanhH]

bgfx might make it easier but put a pin on that until 0.10 or post release