Professor CRUD endpoints

Create all basic endpoints for the professor db table. Anyone can create a professor, but then later only administrators and the person, that created the prof initially should be able to edit or delete it.
The Profile picture (pfp) should only be a link, you can enforce this rule using the class validator.

Start by locating the professor database model and existing CRUD endpoint patterns, then read the project's authentication and class-validator conventions. Done means basic professor create, read, update, and delete endpoints exist, profile pictures accept links only, and edits or deletion are limited to administrators or the original creator.

Written by the indexing model from the issue text.