Resolve "Notify students when they cannot be found by TA"

What does this mr do?

This mr adds a new not found notification. Students will receive this notification if the TA clicks the 'not found' button.

Screenshots

before

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 #245 (closed)