Add tests for custom rules configuration

[romaricpascal]

What

Add tests testing the configuration of the rules we've explicitely enabled in css-rules and scss-rules.

Why

So we're sure our configuration behaves as intended, particularly with the regular expressions used for naming patterns

Who needs to work on this

Developers

Who needs to review this

Developers

Done when

• The test suite for the configuration gives us more confidence that the linting behave as we intend.