This is the first step of improvements over keypairs/keycards/accounts.
- `SyncKeypairFull` protobuf removed
- `SyncKeypair` protobuf is used for syncing all but the watch only accounts
- `SyncAccount` is used only for syncing watch only accounts
- related keycards are synced together with a keypair
- on any keypair change (either it's just a keypair name or any change made over an
account which belongs to that keypair) entire keypair is synced including related keycards
- on any watch only account related change, that account is synced with all its details
- old `accounts` table is moved/mapped to `keypairs` and `keypairs_accounts`
- `keycards` table has foreign key which refers to `keypairs.key_uid`
- `Keypair` introduced as a new type
- api endpoints updated according to this change
