CHG modify format for new repos to use netid instead of github username

[wabscale]

This will be an easy change to implement, but very very difficult to handle. New repos are named based off of: https://github.com/GusSand/Anubis/blob/6717f3bd1c8ec4ad9415aa3a4390d8739bf86e28/api/anubis/utils/github/repos.py#L63-L70

We will need to be super careful to make sure that all of the existing repos, and assignments will still work. Mainly the logic for handling webhooks will need to be revisited and rewritten: https://github.com/GusSand/Anubis/blob/6717f3bd1c8ec4ad9415aa3a4390d8739bf86e28/api/anubis/views/public/webhook.py#L50-L203

We'll also need to make sure that assignment repo collaborators are updated when a user updates their github username: https://github.com/GusSand/Anubis/blob/6717f3bd1c8ec4ad9415aa3a4390d8739bf86e28/api/anubis/views/public/auth.py#L187-L219

One thing that is possible is that we could rename all existing assignment repos (like a migration on github) and update the assignment repo database entries. We can rename repos using the github rest api