Create a button and a status UI to set a post as "solved" or "unsolved"

[tu2463]

Step 1:
On the post details page, create a button on the menu bar. Clicking on the button will switch the post to solved or unsolved.
This button is only shown to the author of this post or TA/professors. Other students won't see the button.

Step 2:
On the category page, show whether the post is solved or unsolved next to each post.

Estimated effort: 8h
Dependencies: none
Acceptance criteria:

• Log in as a student.

• Create a post. Confirm that the post status shows "unsolved" on the category page.

• In the post detail page, click the button to set the post to be "solved".

• Confirm that the post status shows "solved" on the category page.

• Open a post by another user. Confirm that you can't see the solve/unsolve button.

• Log in as a TA/professor

• In the post detail page, change a post's solved/unsolved status. Confirm that you can change the status of posts by all users.

• Confirm that each time you change the status, the post's status in the category page will also change correspondingly.