Add search bar UI to each category page

[AutumnQiu99]

Details:
-Add search bar input field next to the topics toolbar button on each category page
-Place search button next to the input field, that when clicked starts the user's search

Estimated effort: 3-5 hours

Initial assignments:

• Assigned to @ameliakratzer-code

Milestone: sprint 2

Acceptance criteria:

• A user can locate a search bar on any category page that they have permission to visit.
• A user can type queries into the search bar and trigger search by pressing "Enter" or clicking a "Search" button.