- Refactor usages to []Unstructured to use UnstructuredSet
- Add UnstructuredSet.Equal to handle set equality comparison
- Avoid updating tests to prove reverse compatibility
(except: Graph.SortObj, which returns a list of sets)
- Refactor usages of []ObjMetadata to use ObjMetadataSet
- Move Union, Diff, Contains, Hash, Remove, and Equal into
ObjMetadataSet
- Add ToStringMap and FromStringMap for inventory serialization