This is a fpreliminary codecov report addition.

I've added a basic tests file, used Claude to generate some basic tests for the submission checker, and gone from there.

The report can be seen here: https://app.codecov.io/github/mlcommons/inference/tree/arav-codecov-impl

Notes:

• I still need to add the mlcr integration tests to this if possible, as currently this doesn't utilize them and only uses pytest.
• The system currently only looks at PRs to this branch, not master. I want to make sure buy-in exists for adding tests before I start trying to figure out if I should include more, and I need to confirm my testing completeness is correct.