* Remove username from UI code
* Remove username from tests
* Remove username from database
* Modify server endpoints for removing username
* Implement backend aspects of removing username
* Update API docs
* Add name to fleetctl
- Add policy.rego file defining authorization policies.
- Add Go integrations to evaluate Rego policies (via OPA).
- Add middleware to ensure requests without authorization check are rejected (guard against programmer error).
- Add authorization checks to most service endpoints.