Integrate video encoder with va-api support with Rust

[ctrlaltf2]

Likely would be libavcodec in Rust. Va-api is a stretch goal to get hardware-accelerated support in. Needs to be able to get raw video frames/packets/components out to send over a connection, e.g. QUIC or most likely WebSockets because everything's all drafts still after all these years.

[ctrlaltf2]

• gstreamer looked both too complex and not low level enough to pull out packets. Cool framework though.
• most likely will be using ffmpeg-related tech. ac-ffmpeg looks promising.
• moq-rs also apparently integrates something ffempg-related AND exports it directly as a WARP stream under the moq-pub package, that may be the path forward here.

[ctrlaltf2]

Blocked until moq-rs integrated. Likely will be adapting moq-pub tool to be a library. Some work will need to be done to handle audio, potentially will be its own issue included in upcoming libretro issues.