fixed question examples

[nelson-lojo]

There was a de-sync of the contents in questions/ where the pl-faded-parsons-examples/ directory was lost. This PR recovers this and also organizes the content that overwrote it into questions/cs194-sp2023-graph-algs/ and questions/pl-faded-parsons-examples/

edit: provide organization folders

[SybelBlue]

This is blocked until we can get these other things done:

• Update the pl-faded-parsons element
• Re-run the generator to make sure the examples still build
• Check that prairielearn/prairelearn and ucbcbt/ucb-prairielearn:latest both build with the examples out of the box
• Make at least one pushed commit to rerun the CI, and fix any changes.

edit: CI is not broken anymore