This adds a step after login to complete security for your new session. At the
moment, the only verification method is entering your SSSS passphrase, but nicer
paths will be added soon.
This new step only appears when crypto is available and the account has
cross-signing enabled in SSSS.
Fixes https://github.com/vector-im/riot-web/issues/11214
If we trust the key backup at upgrade time then we can sign it so
key backup will work automatically when cross-signing is trusted.
If we don't sign it at this point we'll end up with cross-signing
and key backup set up but key backup untrusted by the cross-signing
key which is a bit of a broken situation.
With https://github.com/matrix-org/matrix-js-sdk/pull/1144 fixes
https://github.com/vector-im/riot-web/issues/11747
This adds dialogs for creating and accessing secret storage via a passphrase or
recovery key. These flows are adapted from the ones used for key backup.