GT4Py language and lowering work that is not about generics. proj-c89c33
holds the generics line; this holds everything else the ICON4Py side ends up
waiting on -- reductions, scans, staggering and their like.
Written during the cycles 37 and 38 sync, because a pitch must hang off a
project and "Strange reductions" had been filed directly under the GT4Py
product. It is a home, not a shaped plan: nothing here has been bet.