feat: Add support for setting the redis username when using redis persistence.

[hexedpackets]

Requirements

• I have added test coverage for new or changed functionality
• I have followed the repository's pull request submission guidelines
• I have validated my changes against all supported platform versions

Describe the solution you've provided

eredis supports taking in a username for connections in addition to the password. The default is undefined, which will remain unchanged unless redis_password is explicitly configured.

[kinyoklion]

@hexedpackets Thank you for the contribution! This seems like a reasonable addition. It may take a little bit to review and validate.

[kinyoklion]

@hexedpackets It appears that some changes will be needed to get the unit tests passing.

[hexedpackets]

@hexedpackets It appears that some changes will be needed to get the unit tests passing.

Tests are passing but there was a typo in the type spec. I pushed up a fix for that and dialyzer is passing locally for me now.

Side note - might be worth adding an instruction to run make dialyze in the CONTRIBUTING.md document. I didn't realize that it ran separately from the tests task until it failed in CI.