Integrate Octave on ExamCooker (global EC room)

[theg1239]

• Add a widget to access Octave via ExamCooker so people can listen and play to songs globally on ExamCooker
• They can vote on them
• Currently Octave doesn't support each user playback, so changes would have to be made on the upstream Octave codebase to support a mode that allows this
• Playing the actual music would not require any API keys, it would occur via YT iframes, using react-player to render a nice custom UI over it, inspired by the UI on everything-assistant.com