Add a check to ensure that we find crypto data in the crypto store
when we're restoring a session and otherwise abort the session restore.
This will prevent us from restoring a session and generating new keys
when there was a previous session with different keys.
***This will force a logout for all users***
See the linked issue (and the comment in code) for more detail.
Fixes https://github.com/vector-im/element-call/issues/464