Make full user name available to UI extension

Currently the JS library for UI extensions only passes the userid (ui.user), but not the users' full name.

We could update the user info to ui.user.id for the username, and ui.user.name for the full name.

It is not sure if we pass the full name to the Channel Manager yet.

If adding the full name is too much work now, we should only rename ui.user to ui.user.id. That leaves room to add more user properties in the future while remaining backwards-compatible.