`last_update_clock` will be used later for synchronization.
All keypair functions take clock value in consideration when
making a decision whether to perform an action or not.
Due to easier maintaining in future the following is done:
- keypairs table removed
- keycard table added, storing only keycards/keypairs
- keycard_accounts table added, storing only accounts migrated to a keycard
Migration is done keeping the current keycard state accurate (no keycard records will be lost).
Handling results of `GetAllMigratedKeyPairs` and `GetMigratedKeyPairByKeyUID`
endpoints updated in a way that account address is unique in the address list.
Sale Djenic
Andrea Maria Piana