Add plagiarism checker

[Dimitris-Toulis]

This PR adds a plagiarism checker workflow (fixes #681). It runs for every art PR and compares the added art code to all other submissions. The workflow is a modified version of the sprig plagiarism checker ( differences: structure pass, folder structure of submissions and other minor things )

How it works

• It uses compare50 and the structure and text passes. The structure pass ignores whitespace, comments and variable names while the text pass ignores only whitespace and comments.
• If the structure score is > 50% it is flagged as plagiarism and a comment is made by github-actions giving the structure and texts passes scores.
• An action artifact named compare50-results is generated with an html file detailing the results for every score >10% match ( < 10% matches are not useful as a simple nested for loop triggers a small match )

You can see a demo in the fork pull requests The copied art fails the check and the comment is triggered while the original one passes the check

Relevant slack link

[vercel[bot]]

@Dimitris-Toulis is attempting to deploy a commit to the Hack Club Team on Vercel.

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[Dimitris-Toulis]

You can also tweak the thresholds if there are any false positives, they are in line 19