Add integration testing in CI

[rajarshimaitra]

Currently our code coverage tests are only including unit tests. Which provides almost no coverage in the handlers and utils module. This can be improved by adding the integration tests into CI codecov jobs.

[notmandatory]

The bdk lib has switched to using https://coveralls.io/ because it has more accurate code coverage. Either in the PR for this issue or in a separate PR we should also switch bdk-cli to coveralls.