Add new state "published"

[ldang]

The admin user should be able to add a "published" state to the room talks, to indicate that the talk has been split and uploaded already.

This would give us more flexibility in our current workflow and automate the bookkeeping.

It would be better and more intuitive if we add a "published" state, and if all the talks in a room_track are published, then we can reflect that on the front page too.

Currently, we are making sure the full room track is done before we split and upload it. We also have to remember if it's published or not and annotate the room stream.

For example, below, it would be nice to go from Done (which indicates it's ready to split and upload) to Published, which means we've completed the split and upload.

[ldang]

The long-term plan is that the admin user should be able to select a button on the webapp, and kick off automation to split and upload talks. We still need to work on the backend automation, and put in some protections.