Implement user contexts

[exlted]

At some point, multiple users should be allowed to have access to the same instance of StreamCore. To handle this we'll need user contexts when entering any StreamCore hosted sites, or when using any per-user functionality.

This is not expected to set up separate ingests in the same instance, these users would have access to the same ingests, the output functionalities however would be associated with their accounts specifically.

This will allow moderators access and control over the same chat ingests that the streamer has,