WIP: Allow initial kinds of ATs to depend on earlier ATs' initial kinds
Related to #12612.
Slightly changes associated type kind inference to extend the kind environment immediately after getting an AT's initial kind (in getInitialKind), before proceeding with kind inference/checking of subsequent ATs. Previously, the kind environment was only populated with new AT kinds after finishing all AT kind inference/checking in kcTyClGroup.
This change allows some associated types to refer to previously kind-checked/inferred associated types while kind checking.