Show TA attendance per lab under course status

What does this mr do?

Fills in the assistants tab in course status where info is shown about the assistants during a certain lab of the course. For now it only shows the amount of requests handled.

Screenshots

after

Does this MR meet the acceptance criteria?

• I have added a changelog entry to reflect the significant changes I made.
• Tests were created to test the feature.
• I have updated the documentation accordingly.
• I adhere to the style guide.

Closes #172 (closed)