A signal type `wallet` which had an event `type` set to `sing-transactions` is now a new signal
type `wallt.sing.transactions` with event which represents list of transactions that need to be signed.
- Moved some methods from Transactor to users of it to clean interface.
- Mocked Bridge interface and Transactor interface for tests
- Wrote unit tests for SendTransaction
- exported API methods left at the same place
- private methods moved to helpers.go
- stuff for testing moved to testutils.go
- created storage interface with clean API and multi transaction related db calls moved
to MultiTransactionDBStorage implementation
- created dummy in-mem storage for tests with multi transactions
- written tests for MultiTransactionDBStorage
A leftover after migrating to incremental activity updates session-based
We now use pending instead of `multi-transaction-update`, there is no
multi-transaction update without an equivalent pending or transfer update
Reading the Nonce from the local cache may be incorrect if the tx is made out of the Status app or
if Status app sends a tx prepared by the dapp (via WalletConnect). A submitted tx with a wrong Nonce
results in a failing tx, that's why we need to read the Nonce from the network.