Refactored SubmissionFilePanel subcomponents into functional style

[david-yz-liu]

Proposed Changes

(Describe your changes here. Also describe the motivation for your changes: what problem do they solve, or how do they improve the application or codebase? If this pull request fixes an open issue, use a keyword to link this pull request to the issue.)

This pull request does some refactoring of the React components in the grading view.

1. Switched AnnotationManager, DropDownMenu, FileSelector, and FileViewer to memoized functional components.
2. Removed unused ref in SubmissionFilePanel.
3. Modified FileViewer to set loading state to true whenever its file-related props change, so each child component (TextViewer, PdfViewer, etc.) calls only setLoadingCallback(false) when it is done loading.
4. Added loading spinner to FileViewer and removed the attempt from pdf.js to use a custom spinner (which was failing to load anyway).

Screenshots of your changes (if applicable)

Associated documentation repository pull request (if applicable)

Type of Change

(Write an X or a brief description next to the type or types that best describe your changes.)

Type	Applies?
🚨 Breaking change (fix or feature that would cause existing functionality to change)
✨ New feature (non-breaking change that adds functionality)
🐛 Bug fix (non-breaking change that fixes an issue)
🎨 User interface change (change to user interface; provide screenshots)
♻️ Refactoring (internal change to codebase, without changing functionality)
🚦 Test update (change that only adds or modifies tests)
📦 Dependency update (change that updates a dependency)
🔧 Internal (change that only affects developers or continuous integration)

Checklist

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Before opening your pull request:

• I have performed a self-review of my changes.
  • Check that all changed files included in this pull request are intentional changes.
  • Check that all changes are relevant to the purpose of this pull request, as described above.
• I have added tests for my changes, if applicable.
  • This is required for all bug fixes and new features.
• I have updated the project documentation, if applicable.
  • This is required for new features.
• If this is my first contribution, I have added myself to the list of contributors.

After opening your pull request:

• I have updated the project Changelog (this is required for all changes).
• 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 by Coveralls.
• I have requested a review from a project maintainer.

Questions and Comments

(Include any questions or comments you have regarding your changes.)

[coveralls]

Coverage Report for CI Build 26693782648

Coverage remained the same at 90.277%

Details

• Coverage remained the same as the base build.
• Patch coverage: 10 uncovered changes across 5 files (35 of 45 lines covered, 77.78%).
• No coverage regressions found.

Uncovered Changes

File	Changed	Covered	%
app/javascript/Components/Result/file_viewer.jsx	33	27	81.82%
app/javascript/Components/Result/dropdown_menu.jsx	9	8	88.89%
app/javascript/Components/Result/html_viewer.jsx	1	0	0.0%
app/javascript/Components/Result/image_viewer.jsx	1	0	0.0%
app/javascript/Components/Result/pdf_viewer.jsx	1	0	0.0%

Coverage Regressions

No coverage regressions found.

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Coverage Stats

Relevant Lines:	49901
Covered Lines:	46018
Line Coverage:	92.22%
Relevant Branches:	2149
Covered Branches:	971
Branch Coverage:	45.18%
Branches in Coverage %:	Yes
Coverage Strength:	121.84 hits per line

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💛 - Coveralls