Feature request: Support FSR 3 instead of FSR 1

[LDprg]

Bgfx does support FSR 1, however it is a bit outdated since we have FSR 3 nowadays.

FSR 3 does result in way better performance and quality (more details and less flickering). There is also no real downside of implementing it (besides the one time effort in implementing it) as the platform compatibility did not change.