ImmutableOrdered{LeafSet,Map}NodeBuilder should provide insert/move operations

As per RFC8072 and RFC8040, RESTCONF and other applications need to be able to efficiently manipulate the order of entries.

As a first step, builders should allow efficient implementation of move and insert operations, when being instantiated from a built instance, so that users can manually instantiate replacement lists, without having to resort to manual traversal.

While this does not directly improve situation for DataTree operations, it allows users to more efficiently read-modify-write the contents of the data tree and manipulate these structures when in custom use.