ENG-6071 Allow partition column and replicate/partitioning changes on empty tables

This has most of the code for unique indexes and other changes, but doesn't have the CatalogDiffEngine code or the supporting tests yet.
I'm slightly off-put by the fact that we can't do this within checkModifyWhitelist() but I know how you got here and I'm not sufficiently offended to make a federal case out of it.