Cohorts for social log in

Following the MAS migration, it is no longer possible to use ``` ``` to determine social log in provider.

@sandhose left these notes on how to work around the problem.

Yep. The table you want to look at:

• users have user_id, username (localpart), created_at, locked_at, deactivated_at
• user_sessions are 'MAS cookie sessions', so a login in the MAS UI, used both to manage your account and actually login in a client. It has user_id, created_at, finished_at, user_agent (the one from the browser, not indexed though!), last_activity_at, last_active_ip
• compat_sessions are compatibility sessions, either m.login.password or m.login.sso. They have user_id, created_at, finished_at, last_active_at, last_active_ip, user_agent (of the client which did the /login request)
• oauth2_sessions are next-gen auth sessions. They have a oauth2_client_id (letting you identify the client though the oauth2_clients table, created_at, finished_at, last_active_at, last_active_ip, user_agent (of the client which did the OAuth 2.0 token request)