Update CodeCov to include integration tests

[billschereriii]

Description

CodeCov coverage statistics do not currently take integration tests into account, just unit testing. This should be expanded to present an accurate picture of our code coverage. The root of the issue is that LCOV does not use the integration tests in its report, so LCOV's report should be expanded to account for the integration tests.

Justification

Using all tests in the coverage report provides a better reflection of what areas of the code base still need to be tested.

Implementation Strategy

1. Either generate a separate coverage report with LCOV for the integration tests and then merge with the coverage report generated by the unit tests, or run both the unit tests and integration tests at the same time, generating a single coverage report with LCOV.
2. Tweak CI to ensure both integration test coverage and unit test coverage are uploaded to CodeCov.

Acceptance Criteria

• Generate integration tests coverage report
• Combine integration coverage and unit test coverage into a single report
• Upload the combined coverage report to CodeCov through GitHub Actions