fix: add support for custom config files in commands

[michalsn]

Description This PR resolves an issue where commands could not function when an alternative config file was specified for the queue.

To address this, a new -config option has been added, allowing developers to specify the namespace for the alternative config file.

Fixes #57

Checklist:

• [x] Securely signed commits
• [x] Component(s) with PHPDoc blocks, only if necessary or adds value
• [x] Unit testing, with >80% coverage
• [x] User guide updated
• [x] Conforms to style guide