- Get rid of InsertTestMultiTransaction function in test utils and
use InsertMultiTransaction method of transaction manager
- Use MultiTransaction type instead of TestMultiTransaction
Added a missing wallet DB migration file for multi transactions
`getLogs` for multiple accounts simultaneously. For now only used for
new transfers detection. Detection of `new` transfers has been changed,
now they are searched from head and forward. Previously they were
searched from last scanned block forward.