Fix remarks for annotations on autograder output

[damianhxy]

Description

When annotation.position = -1, set filename to Autograder Output instead.

Motivation and Context

A bug noted by the 122 team is that annotations on the autograder output (when annotation.position = -1) appear to reference the last file in the file tree instead.

Looking at viewFeedback.html.erb, the current logic for choosing filename is @files && annotation.position ? Archive.get_nth_filename(@files, annotation.position) : @submission.filename.

When we have a single file submission, @files is nil and so filename is @submission.filename (i.e. the last file).

Similarly, with an archive submission, filename is Archive.get_nth_filename(@files, annotation.position), which evaluates to @files[annotation.position][:pathname] where annotation.position = -1. In particular, we are accessing index -1, i.e. the last file.

This PR remedies the logic by explicitly handling the annotation.position = -1 case.

How Has This Been Tested?

• Create an autograded assessment that accepts archives (for simplicity, use the assessment from Disable version switching feature when displaying autograder output #1578).
• Add an additional Style problem.
• Make a submission, annotate the autograder output, and release grades.
• View feedback page (by clicking on the autograded score on the view assessment page)

Before changes

After changes

Types of changes

• Bug fix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)
• Breaking change (fix or feature that would cause existing functionality to change)

Checklist:

• I have run rubocop for style check. If you haven't, run overcommit --install && overcommit --sign to use pre-commit hook for linting
• My change requires a change to the documentation, which is located at Autolab Docs
• I have updated the documentation accordingly, included in this PR

[victorhuangwq]

LGTM

[victorhuangwq]

Ah so this is a TODO for the future?

[victorhuangwq]

Let me tag @michellexliu here to take note

[damianhxy]

Yup, it is a TODO to track the second "bug" reported by the 122 team (The order of annotations in the student feedback when they click on the score is not the same as the order when you look at the file page)