P2Fancy: SourceAcademy GitHub Classroom with central repository

[chekjun]

Description

Type of change

• Bug fix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)
• Breaking change (fix or feature that would cause existing functionality to not work as expected)
• This change requires a documentation update
• Code quality improvements

How to test

1. Request to join the test GitHub classroom named 'source-academy-course-test'.
2. Request to be added as member of the GitHub Organization 'source-academy-course-test'.
3. Run Source Academy on localhost.
4. Click on Classrooms in the primary (topmost) navbar.
5. Click login and sign in with your GitHub account.
6. Select course 'source-academy-course-test'.
7. Click on Missions (there should be 3 visible mission cards with their accept buttons).
8. Click on accept for any of the missions and follow the procedure to accept the GitHub Classroom assessment.
9. Click on Missions again (the 'accept' button should change to 'open').
10. Click on Quests (there should be 1 visible quest card with accept button).

Checklist

• I have tested this code
• I have updated the documentation