Pc alex put operation course suggestion2

In this PR, we suggest some changes to AlexPutOperationCourse

All of the changes in pc-AlexPutOperationCourse-suggestion (including refactoring the linear search to be a query
Using an existing exception instead of creating a new one
Using status code 403 instead of 404 when the intent is to show that an operation is not permitted due to security reasons.

ucsb-cs156-f23 / proj-organic-f23-6pm-1