Not pseudo takes selector

[sebastiaanvisser]

The :not() pseudo selector now takes a Selector as argument, not a Text. This is closer to the CSS semantics and allows reuse of Clay selector syntax.

Note that this change will break the API and needs a bump. You can still just use string literals as arguments with OverloadedStrings, so the impact is likely very limited.

Additionally I made a small fix in the selector parser by reusing the refinement parser internally. This means now things like ":first-child" and "@data-foo" will parse properly. (using with star internally).

Not super relevant for now, but PseudoFunc is modelled to always take Text arguments, which is somewhat weakly typed and requires the :not() selector to convert to text immediately. Better model the actual function arguments types (e.g. Text | xn+k | Selector) to allow future inspection / optimizations etc, but I'm pretty sure no one is relying on that any time soon.