Part of Support Nested Stacks and Updates story
To add nested stack support to Valet, make up for missing Heat resource
Orchestration IDs in nested resources by generating a subset of Heat stack
lifecycle scheduler hints for each resource in advance, store them as opaque
metadata in Valet, then leverage the metadata at Nova scheduling time. Make
additional accommodations in anticipation of complexities brought about by
adding support for stack updates.
Change-Id: Ifed5b0f8172e522caf7e520f8131f23d4d336f4f
Story: #2001139
Task: #4855
3aa88d65ad