- 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
- handling `null` values in the Hop response
- using data returned from the Hop api when preparing data for estimation and calling `swapAndSend` and `sendToL2`
- estimating gas for bridges implemented in the bridges implementation types, avoiding wrong gas for placing bridge transactions