operate on `HirId` in `hir::Pat::each_binding`, and consequences of that

operate on `HirId` in `hir::Pat::each_binding`, and consequences of that

Changing the `each_binding` utility method to take the `HirId` of a
binding pattern rather than its `NodeId` seems like a modest first step
in support of the `HirId`ification initiative #50928. (The inspiration
for choosing this in particular came from the present author's previous
work on diagnostics issued during liveness analysis, which is the most
greatly affected module in this change.)