Supporting work discussion notes

[nwalters512]

This issue serves to capture some notes and thoughts about barcode scanning and more generally about the attachment of "supporting work" to submissions. Barcode scanning is implemented in part in #5190 and #5192.

• We should add obvious registration markers to generated pages so that we can easily identify where the barcode is on the page and at what scale it's at.
• We should have some integrity checks when it comes to scanning and entering barcodes on pages.
  • Once a barcode PDF has been scanned, we should disallow entering that barcode in a question.
  • Add "only match to submissions between date/time X and Y" and/or "only match to submissions for courses X, Y, and Z"
  • Need to not make this too restrictive - for instance, a given student should be able to upload the same piece of paper to multiple parts of one question, or to multiple questions on the same exam.
  • If two students independently enter the same barcode, or a student enters the same barcode across multiple assessments, or (more conditions here), we should surface that as a potential academic integrity issue to students.
• We should unify the "upload supporting work" so that it functions the same whether a student enters a barcode or uploads a file. We should also allow students to capture supporting files via their camera directly from the browser.
• Supporting work should maybe be available via both an element and functionality built-in to PrairieLearn.
  • The element could be used to integrate supporting work into the flow of questions and to allow for the assignment of points to different bits of supporting work.
  • The built-in functionality could be enabled automatically for all questions, or explicitly for some questions, or only when students are on an exam-mode network, etc.
  • Need to think carefully about when/how this is enabled.