Add APIs to support manage and unmanage share snapshots.
Also add support in the Generic driver.
This only supports for DHSS=False driver mode.
Add provider_location column to the share_snapshots table
to save data used to identify the snapshot on the backend.
Also need to bump microversion.
APIImpact
DocImpact
Change-Id: I87a066173c85d969607d132accd9f0e9bd49c235
Implements: blueprint manage-unmanage-snapshot