Stylelint pattern for selector-nested-pattern doesn't match valid selectors

[fabiankaegy]

The pattern we have in place for the selector-nested-pattern rule are not currently allowing :where( .something & ) selectors which are pretty important when you need to avoid overly specific styles. We should update the pattern to allow for these.

[fabiankaegy]

We discussed this in the Toolkit Working group. What we landed on is that we would look into potentially removing this check entirely because it is matching way too many false posives...

Alternatively we could update it to only error for attempts to use the & for string concatination which is not supported