Fixups for categoricals

This PR will collect the various fixups for Categorical.

See #8078 for the ToDos.

In the end should Close: #8074


Closes: #8077 -> API/FIX: wrap result cut/qut in Series and make it ordered
why is this on the fastpath? the point of the fastpath is that almost no checking is done (and its completely internal), so it is truly the fast path