homectl: store FIDO2 up/uv/clientPin fields in user records too

homectl: store FIDO2 up/uv/clientPin fields in user records too

This catches up homed's FIDO2 support with cryptsetup's: we'll now store
the uv/up/clientPin configuration at enrollment in the user record JSON
data, and use it when authenticating with it.

This also adds explicit "uv" support: we'll only allow it to happen when
the client explicity said it's OK. This is then used by clients to print
a nice message suggesting "uv" has to take place before retrying
allowing it this time. This is modelled after the existing handling for
"up".