Instructor Coverage Estimate and Preferred Hiring Level Feature

[jeff-zhang12]

Summary: Added drop down selection for preferred hiring level in the application review dialog. This is then used calculate an estimated coverage and to display the instructors preferred hiring level in the coordinator view.

Changes:

• Adds a one to many relationship from the hiring_level_entity to the application_review_entity that stores the preferred hiring level for each application review
• Added drop down to application_dialog
• Added icon indicating preferred hiring level to edit-assignment.dialog and quick-create-assignment.dialog
• Added icon showing estimated coverage to hiring-preferences.component
• New endpoint at /api/hiring/{course_site_id}/enrollment. Only callable by the instructor of the course and returns total enrollment in that course
• Small UI fix in hiring-admin.component
• Small fix for calling unsubscribe on undefined subscriptions, causing errors when viewing application-dialog from edit-assignment.dialog and quick-create-assignment.dialog

Screen.Recording.2025-12-01.at.1.07.42.PM.mov

[jeff-zhang12]

Accidentally merged the other features into this branch somehow. Will fix.