feat: adds WebRTC (MediaMTX) support

[pedrolamas]

Adds support for WebRTC MediaMTX camera.

Testing can be done with Docker!

• Start the container with the following (change "192.168.20.60" to test machine local IP!):

  docker run --rm -it -e MTX_PROTOCOLS=tcp -e MTX_WEBRTCADDITIONALHOSTS=192.168.20.60 -p 8554:8554 -p 1935:1935 -p 8888:8888 -p 8889:8889 -p 8890:8890/udp -p 8189:8189/udp bluenviron/mediamtx:latest-ffmpeg

• With container running, open http://localhost:8889/mystream/publish
• Select a camera, change settings as required, click "publish"
• In Fluidd, add a new "WebRTC (MediaMTX)" camera, set streaming url to http://localhost:8889/mystream
• Save and test

Resolves #1407