Feedback Files: Ensure submission association if it exists

[pretendWhale]

Motivation and Context

the API feedback_files.index method currently does not return any feedback files, because it calls submission.feedback_files but feedback files are not currently associated with submissions directly. This PR adds that association, if a submission exists for the test run.

Your Changes

Description:
Modified test_run.update_results! to add submission association if one exists.

Type of change (select all that apply):

• Bug fix (non-breaking change which fixes an issue)

Testing

Tested via the markusapi package, as well as adding tests.

Questions and Comments (if applicable)

If a submission exists when test results are processed, marks are created due to a call to set_autotest_marks in update_results!, even if the tests have failed. I don't think this is a problem, but there may be cases I'm not considering.

Checklist

• I have performed a self-review of my own code.
• I have verified that the pre-commit.ci checks have passed.
• I have verified that the CI tests have passed.
• I have reviewed the test coverage changes reported on Coveralls.
• I have added tests for my changes.
• I have updated the Changelog.md file.

[coveralls]

Pull Request Test Coverage Report for Build 7227088947

• 17 of 17 (100.0%) changed or added relevant lines in 2 files are covered.
• No unchanged relevant lines lost coverage.
• Overall coverage increased (+0.003%) to 91.565%

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Totals
Change from base Build 7226755465:	0.003%
Covered Lines:	38550
Relevant Lines:	41480

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💛 - Coveralls