feat(cardano): add support for CIP36 governance registration format

[davidmisiak]

This PR adds support for CIP36 governance registration format. Changes:

• New field: delegations array (each delegation consists of a voting key and its voting power proportion) as an alternative to delegating the entire voting power to a single voting key. The array is embedded in the protobuf message due to simplicity (max. 32 delegations).
• New field: voting_purpose integer (currently 0 = Catalyst, 1 = other). For CIP36 registrations, this field is always serialized, (value 0 is used if not provided by the client).
• All Catalyst occurences are replaced by governance, since the format should be usable for other governance purposes, not only Catalyst.
• The ed25519_pk bech32 prefix is replaced by gov_vk for the purpose of displaying voting public keys.

The new 1694' derivation path and the vote cast call implementation is not included in this PR.

[gabrielKerekes]

Looks good in general. I left just a few small suggestions.

As mentioned offline - I wasn't able to compare the auxiliary data hash with cardano-cli so please investigate. The produced data look good to me though.

[gabrielKerekes]

@davidmisiak One thing I noticed while reviewing the connect PR. Maybe we could display "Voting purpose: Catalyst" and "Voting purpose: Other" for voting purpose 0 and other respectively. What do you think?

[davidmisiak]

@davidmisiak One thing I noticed while reviewing the connect PR. Maybe we could display "Voting purpose: Catalyst" and "Voting purpose: Other" for voting purpose 0 and other respectively. What do you think?

What about Catalyst / 1 (other) / 2 (other) / etc.? @janmazak what do you think?

[janmazak]

@davidmisiak One thing I noticed while reviewing the connect PR. Maybe we could display "Voting purpose: Catalyst" and "Voting purpose: Other" for voting purpose 0 and other respectively. What do you think?

What about Catalyst / 1 (other) / 2 (other) / etc.? @janmazak what do you think?

I think the number should be displayed even in case there is some text. Esp. because "other" might expand in the future. If there is enough space on the screen, go for it (I won't do anything on Ledger, I guess it's not worth the additional code size --- you have to declare tmp buffers etc. to concatenate strings in C).

[davidmisiak]

Merged in trezor#2561