Before this change, Authorize() method was just returning an error,
regardless of whether the user is unauthorized or whether there
is some other unrelated error. Returning boolean with information
about user authorization and error (which should be unrelated to
the authorization) separately will make it easier to debug.
Fixes#27974
* Improper format specifier (e.g. %s for bools or %s for ints)
* More or less parameters than format specifiers
* Not calling a formatting function when it should have (e.g. Error() instead of Errorf())
Added function to read basic ACL from a CSV file.
Added implementation of Authorize based on that file's policies.
Added docs on authentication and authorization.
Added example file and tested it.