By default the homeserver will use the identity server used during the
binding of the 3PID to unbind the 3PID. However, we need to allow
clients to explicitly ask the homeserver to unbind via a particular
identity server, for the case where the 3PID was bound out of band from
the homeserver.
Implements MSC915.
Older identity servers may not support the unbind 3pid request, so we
shouldn't fail the requests if we received one of 400/404/501. The
request still fails if we receive e.g. 500 responses, allowing clients
to retry requests on transient identity server errors that otherwise do
support the API.
Fixes#3661
This implements this very crudely: this probably isn't viable
because parting a user from all their rooms could take a long time,
and if the HS gets restarted in that time the process will be
aborted.
Make sure that we delete devices whenever a user is logged out due to any of
the following situations:
* /logout
* /logout_all
* change password
* deactivate account (by the user or by an admin)
* invalidate access token from a dynamic module
Fixes#2672.
Non-functional refactoring to move deactivate_account. This means that we'll be
able to properly deactivate devices and access tokens without introducing a
dependency loop.
