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.