This adds persistence to the Nextcloud server 2FA logic so that the server
knows which 2FA providers are enabled for a specific user at any time, even
when the provider is not available.
The `IStatefulProvider` interface was added as tagging interface for providers
that are compatible with this new API.
Signed-off-by: Christoph Wurst <christoph@winzerhof-wurst.at>
A Two Factor third party App may throw a TwoFactorException()
with a more detailed error message in case the authentication fails.
The 2FA Controller will then display the message of this Exception
to the user.
Working on #26593
Signed-off-by: Lukas Reschke <lukas@statuscode.ch>
