Allow students to re-create deploy keys in the portal

[buedaswag]

1. student creates git repository batchX-workspace
2. Student adds deploy key to git repository batchX-workspace
3. student deletes git repository, but does not delete the deploy key from the repo
4. student creates a new repository batchX-workspace
5. student adds deploy key to git repository batchX-workspace, but it's unable to do so

how can we fix this?

• add a feature to recreate keys for a student in the portal
• add troubleshooting item telling the student to recover repo, delete the key from it and then add to new repo

https://docs.github.com/en/authentication/troubleshooting-ssh/error-key-already-in-use