FAL-242 Implement adding and removing tags from filter

This finishes the implementation for the tag input select.

Screenshots:

Test instructions:

• set up the frontend and backend. Use the backend revision from backend-app-course-search!6 (merged)
• follow test instructions on backend-app-course-search!6 (merged)
• for the tag filters, verify that you can select, apply, unselect tags, and verify that the search results updates as expected

Reviewers:

• @tartansandal