Datum for modules/Resources/Composites

In Hiera, they allow a specific hierarchy for module independent of the global/env ones, yet overridable in the latter.

I really like this idea and it would allow to bundle some data specific to the resource or composite resource, that could be either defined at a layer above of the hierarchy or at runtime on the Node for a resource (not Composite as they're evaluated at MOF compilation time).

To support something similar, DSC Resources could:
- use a locally defined Datum
- feed non-mandatory parameters with Datum lookup (if defined above, they're overridden)

Needs to do a PoC of this...