Encoders: support full 0-255 color range

[Vixea]

Tested with VAAPI, untested with NvEnc. Windows related changes soon.

[Meister1593]

Testing on pico 4 pro, some weird results:
First image is from steamvr view, second is with this pr, third is with this pr + gamma 1.1 (i found some mentions about this issue here)
It seems like by default it's making image way too dark, and if i would compare with some native headset, i think most correct one is with 1.1 gamma or prior to this PR?...
Not sure what is right or wrong there, but native headset (like vive) looks closer to 1.1 or without this pr

[Vixea]

Ok after more testing it turns out not even the previous limited range is correct it may have been closer but it's not correct. A simple 1.1 gamma default change will get us closer to the previous results for the meantime before we can remove the bs that is doing color correction twice which is bound to have mistakes

[Vixea]

What we really need is someone to sit down and figure out if somewhere is implicitly using the wrong color space and if it's not just remove the above bs and or correct both