The FIDO2 cmdlets to hint at missing PIN on connection error.

[JMarkstrom]

The FIDO2 cmdlets should probably hint at missing PIN when failing connection:

                if (YubiKeyModule._fido2PIN is null)
                {
                    throw new Exception("Connect-YubikeyFIDO2 failed to connect to the FIDO2 applet!");
                }
            }