Implement export location metadata feature

Some upcoming features require more than one export location and
possibility to mark them with specific labels like fast/slow or
rw/ro.

So, implement 'export locations metadata' feature:
- It allows to set any key-value pairs for each export location.
- These key-value pairs can be set only by share manager using
  response from various share driver methods.
- Example of update is implemented using Generic driver
  "create_instance" method.
- Metadata can be updated for any export location in any place
  of share manager where db function "share_export_locations_update"
  is called.
- Keys from export location metadata table will be added to 'share' and
  'share instances' views as export location attributes.

Also:
- Add new attr 'is_admin_only' for existing export locations model.
  If set to True, then only admins will be able to see them. Unless
  policy is changed.
- Add APIs for reading export locations by share and share instance IDs.
- Remove 'export_location' and 'export_locations' attrs
  from 'share' and 'share instance' views.
- Bump microversion as new APIs implemented.

APIImpact

Implements bp export-location-metadata

Change-Id: I36d1aa8d9302e097ffb08d239cf7a81101d2c1cb
10 files changed
tree: e68c11da210b72ceb71ceefd9eab540d5fd8acfb
  1. manila_tempest_tests/