The response of ``GET /allocation_candidates`` API provides two fields
of ``allocation_requests`` and ``provider_summaries``. The callers,
like the filter scheduler in nova, would use information in
``provider_summaries`` in sorting or filtering providers to allocate
consumers. However, currently ``provider_summaries`` doesn't contain
resource classes that aren't requested.
With this patch, ``GET /allocation_candidates`` API returns all
resource classes with a new microversion.
Change-Id: Ic491f190ebd97d94c18931a0e78d779a55ee47a1
Closes-Bug: #1760276
Blueprint: placement-return-all-resources