Go livepeer liveportrait

[JJassonn69]

What does this pull request do? Explain your changes. (required)

This pull request implements the go-livepeer side code of the LivePortrait runner.

Specific updates (required)

How did you test each of these updates (required)

The updates were tested using the local orchestrator and broadcaster nodes running in devnet.

The request is very similar to other pipelines in the network. Only difference is the source_image and driving_video for the pipeline. Since the models used are not very specific "default" is used instead.

curl -X POST "http://127.0.0.1:8935/live-portrait" -F model_id="default" -F source_image=@/Users/s0.jpg -F driving_video=@/Users/d6_trim.mp4

Does this pull request close any open issues?

This PR closes the bounty proposal for LivePortrait.

Checklist:

• Read the contribution guide
• make runs successfully
• All tests in ./test.sh pass
• README and other documentation updated
• Pending changelog updated