Restrict which roles can "save" a new answer

[DavidVeits]

Hello!
It appears that any user in a class can select and save answers to a question - and those new answers are then published into the knowledge base. This opens the door to students degrading the quality of the knowledge base, either intentionally or accidentally. Is there a way to restrict which users (or preferably which roles) can save a new answer to a question?

Steps to reproduce:

1. Ask a question, tagging the bot
2. Someone, anyone, responds in the thread with a nonsense or even malicious answer
3. When the bot responds, a student clicks "Tag Teaching Staff"
4. The "Select an answer" dialog appears
5. Anyone selects the nonsense or malicious answer and clicks "Save"
6. The incorrect answer is then saved to the database, and then eventually published to the knowledge base
7. Future students asking the same question from step 1 then may be receive a response that includes the incorrect answer

I would love to know if this is a bug, a feature, or working as intended.

Thanks!
Dave