This patch adds a microversion with a release note for allocation
candidates with nested resource provider trees.
From now on we support allocation candidates with nested resource
providers with the following features.
1) ``GET /allocation_candidates`` is aware of nested providers.
Namely, when provider trees are present, ``allocation_requests``
in the response of ``GET /allocation_candidates`` can include
allocations on combinations of multiple resource providers
in the same tree.
2) ``root_provider_uuid`` and ``parent_provider_uuid`` fields are
added to ``provider_summaries`` in the response of
``GET /allocation_candidates``.
Change-Id: I6cecb25c6c16cecc23d4008474d150b1f15f7d8a
Blueprint: nested-resource-providers-allocation-candidates
41b04e8819