Adds a new placement API microversion that supports specifying multiple
member_of parameters to the GET /resource_providers and GET
/allocation_candidates API endpoints.
When multiple member_of parameters are found, they are passed down to
the ResourceProviderList.get_by_filters() method as a list. Items in
this list are lists of aggregate UUIDs.
The list of member_of items is evaluated so that resource providers
matching ALL of the member_of constraints are returned.
When a member_of item contains multiple UUIDs, we look up resource
providers that have *any* of those aggregate UUIDs associated with them.
Change-Id: Ib4f1955f06f2159dfb221f3d2bc8ff7bfce71ee2
blueprint: alloc-candidates-member-of
368b6d9293