Support up to two PIN protocols

[robin-nitrokey]

No description provided.

[sosthene-nitrokey]

Probably should be an enum rather than just u8

[robin-nitrokey]

I guess there should be an enum in ctap_types. But changing the request field to use the enum would mean that we would return an error for invalid/unsupported PIN protocols already during the deserialization, which might not be correct. More importantly, it would also mean that we return the generic INVALID_CBOR error while this should typically be an INVALID_PARAMETER instead.