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.

[PaulRotmann]

Thanks for this contribution! The functionality you're implementing is definitely needed.

However, there are a few issues that need to be addressed. The code formatting and indentation is inconsistent throughout the changes, and the 4 commits should be squashed into 1-2 meaningful commits. This also represents a breaking change since we currently document that usernames are ignored, so it needs to be part of a major version release. Please also reference issue #133 in your PR description.

The feature itself makes sense for supporting modern Redis versions (6+), but we'll need to plan this as a breaking change for v3.0. Could you clean up the formatting and commit structure? We can then discuss the best approach for integrating this as a major version feature.

Thanks!