Add more de-/serialization tests

[robin-nitrokey]

It is easy to break serialization, for example because enums are serialized using their variant index by default, byte slices are serialized as sequences of integers instead of hex strings, and reordering or removing fields can break serde-indexed. Therefore we should have basic de-/serialization tests for all requests and responses.

• ctap1
• ctap2
• ctap2::client_pin
• ctap2::credential_management
• ctap2::get_assertion
• ctap2::get_info
• ctap2::large_blobs
• ctap2::make_credential
• webauthn