Add CLI script for running workflows on video files

[yondonfu]

This could be useful for testing and developing a workflow without running a WebRTC server which can introduce a bunch of friction especially in remote setups that require the use of TURN servers or opening up UDP ports.

A simple version of the script can wrap ffmpeg to:

1. Convert video frames from the image2pipe muxer into numpy arrays.
2. Convert numpy arrays into tensors.
3. Use ComfyStreamClient to run the workflow on each tensor.
4. Convert tensors into video frames with the rawvideo demuxer.
5. Encode video frames into output video file.

[eliteprox]

This might be a relevant solution https://github.com/Comfy-Org/comfy-action