In microversion 1.34 add a 'mappings' key to each allocation
request. Its value is dict keyed by resource group suffixes
with values of a list of resource providers satisfying that
group.
To preserve symmetry, the mappings key may be sent back when
writing allocations so the schema for POST and PUT allocations
and POST /reshaper are updated.
api history, api-ref and reno are added
Change-Id: Ie78ed7e050416d4ccb62697ba608131038bb4303
Story: 2005575
Task: 33536