linter: `unicorn/filename-case` does not match behavior of original rule

[camchenry]

• original rule only enables kebab case by default where we disable by default
• original rule only looks at name up to first dot, we look at the whole file name

there are also some configuration bugs here and a general lack of testing

[camchenry]

mostly addressed in #6463, still some config options to support but it is much closer to the correct behavior now