Add identity-based TLS auth and UI for client/daemon auth

Turns on TLS by default and uses public keys to authenticate access.

- This PR still may require further testing and input on the user experience.
- FSNotify support has not been added to detect changes to authorized_keys
- Implementation of proposal from #7667

@bfirsh please review and comment on whether this is missing anything needed
We should probably deprecate `DOCKER_TLS_VERIFY` and add a `DOCKER_AUTH` envvar, right?