feat: Enable copying of publicly shared question code (if allowed by instructor)

[SethPoulsen]

implements parts of #9397

[github-actions]

All images

Image	Platform	Old Size	New Size	Change
prairielearn/executor:b941d07f24c161caf92791ca5b755d507f65f8de	null	1187.93 MB	1187.76 MB	-0.01%
prairielearn/prairielearn:b941d07f24c161caf92791ca5b755d507f65f8de	linux/amd64	1187.91 MB	1187.76 MB	-0.01%

[SethPoulsen]

I am aware that this doesn't actually make a way to mark the publicly_shared_source column as true in the database.

Doing that is going to be a bunch of UI design/mess on the question settings page, I thought it would be nice to do that in a separate PR from this.

[codecov]

Codecov Report

Attention: Patch coverage is 55.55556% with 4 lines in your changes are missing coverage. Please review.

Project coverage is 66.89%. Comparing base (22ab7c4) to head (b941d07).

Files	Patch %	Lines
...CopyPublicQuestion/instructorCopyPublicQuestion.ts	0.00%	2 Missing ⚠️
apps/prairielearn/src/lib/copy-question.ts	50.00%	1 Missing ⚠️
apps/prairielearn/src/server.js	75.00%	0 Missing and 1 partial ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##           master    #9800      +/-   ##
==========================================
- Coverage   67.01%   66.89%   -0.13%     
==========================================
  Files         458      458              
  Lines       71353    71351       -2     
  Branches     5720     5703      -17     
==========================================
- Hits        47820    47732      -88     
- Misses      23104    23194      +90     
+ Partials      429      425       -4     

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