Deprecating Pantalaimon and replacing it with generic (one time?) password authentication

[Gnuxie]

Pantalaimon is unmaintained and we warn against using it in our documentation.

It should instead be replaced with some generic password based authentication, that creates a fresh access token that can be used for regular use with the homeserver, a proxy like pantaliamon, or even to then enable rust crypto.

Deprecating Pantaliamon is relatively easy, we can easily find out when it is enabled in the config, or when the password option is provided as an argument.

Designing the new password authentication is harder? Should there even be a config option for the password? Should it always be provided as a file like the secret? Should we even store the access token or display it our quit? What do we do here?