Add prototype dynamic objects map for scene object parts

This allows region modules to add dynamic objects to SOPs rather than having to continually push and pull OSD dynamic attributes.
This is to explore the original MOAP use case for dynamic attributes where it could be very awkward and possibly time-consuming to keep reconstructing MediaEntrys from stored DynamicAttributes.
This commit adds a DOExampleModule to demonstrate/evolve this code.
Dynamic objects involve no storage or persistence changes - the 'backing store' for any data that does need to be saved will remain the DAMap.
DOExampleModule in this commit only attaches a fresh dynamic object.  Actually constructing this from stored dynamic attributes and handling persistence is left for later.
These changes should affect no existing functionality, though it may or may not reveal necessary changes in DAMap down the road.