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
@bfirsh Should this only be set if `*flAuthCa == ""`, if either `*flTls` or `*flTlsVerify` are true then the default values will end up clobbering the new flag values.  I don't think the flags should be used together, but if that is the case we should change the behavior of the `DOCKER_TLS_VERIFY` flag to set the values of the new flags.