* chore_:Don't rely on the master key when generating accounts under the bip 0044 path m/44'/60'/0'/0/0
* fix_: lint issue
* fix_: failed test TestBackendStartNodeConcurrently
- 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