As a developer, I want SSH Keys support in the backend so that I can plumb it into the SSH Keys section on the User Preferences page. See comments by @f0ssel [here](https://www.notion.so/coderhq/V2-Scoping-SSH-Linked-Accounts-Dotfiles-f4e6e2747aaa4225b4b95f215e315fdb#06e3873a2f3d42b09558bfe3d47d6851) <img width="912" alt="SSH Keys section from V1" src="https://user-images.githubusercontent.com/2394436/160974815-3c831a8a-6f41-4223-ba12-125543d568da.png">
