RFE auto detect FIDO2 device

[schaarsc]

during mount, before asking for a FIDO device (used during init) try to find a device.
if there is only one device use this device
if there are no devices or more than one, report the issue and ask for a device (same as now)

[SamBayerZXZ]

Try to use bash for the first one

fido2-token -L | head -n 1 | cut -d':' -f 1

and for the last one in the list

fido2-token -L | tail -n 1 | cut -d':' -f 1