Update codecov and add flag for integration tests

[amontanez24]

Problem Description

As a developer, I want to see the code coverage for our different test suites.

The codecov action we use updated and now requires a token parameter to be used. While fixing this, we should also take this opportunity to flag our different test suites (unit vs integration).

Expected behavior

• Add the token to our workflow
• Add a codecov step to the integration test workflow
• Add flags for unit and integration tests

Additional context

You can follow the changes made in sdv-dev/SDV#2268.