Add support for managing OBS content through the default plugin (Barn)

[dend]

Need to figure out what the best way it is to support integration with OBS. My initial investigations in using the frontend API failed (the API hooks to the window, and it manages all processing within the UI - see feature request), so I need to look for alternatives. Currently that is:

1. Implementing a custom plugin with a communication protocol.
2. Using obs-websocket.

I am leaning towards the latter, since it does the bulk of the important management tasks without having to re-invent the wheel and add another dependency.