* Auth: consistently return same basic auth errors
* Put repeated errors in consts and return only those consts as error strings
* Add tests for errors basic auth cases and moves tests to separate test-case.
Also names test cases consistently
* Add more error logs and makes their messages consistent
* A bit of code style
* Add additional test helper
* Auth: do not expose even incorrect password
* Auth: address review comments
Use `Debug` for the cases when it's an user error
