You can now generate links to join chatrooms with your current user. This can be used to create Docks in OBS for example. This could also be used to generate authentication token to join the chat from 3rd party tools.
* if both local and remote instance have external XMPP connections enabled, the user joins the remote room with his local account
* some code refactoring (builtin.ts)
Note: documentation and settings descriptions are to do.
Related to #112