OptionalonFires for the usual add / remove / rename, and again once a name is bound to its ranges —
defining one is two steps, and getRanges() is null between them. Redefining a name and
undoing onto a different definition recompile through that same path and announce it too.
Wiring notifications are batched per drain, so loading a workbook emits once rather than
once per name. Re-emitted verbatim by the aggregating INamedCollection, which is what
consumers outside the engine listen to.
Called when the names this collection holds, or the regions they designate, change.