Add Redis AUTH user/password support with updated docs and tests

[mauricioguim]

This change implements full ACL-style authentication for Redis 6+ in the Factory class, allowing both username and password to be read from the URI or query parameters and sent as AUTH . The README has been updated to document both legacy (password-only) and new ACL modes in the constructor and callAsync() sections.

In addition, existing tests were revised to expect the three-argument RESP payload when a username is present, and new unit tests were added to verify correct behavior and response handling for URIs supplying both username and password. All changes maintain backward compatibility with single-password authentication.