1. Claim allocations from placement first, then claim specific
   resources in Resource Tracker on destination to populate
   migration_context.new_resources
3. cleanup specific resources when live migration succeeds/fails

Because we store specific resources in migration_context during
live migration, to ensure cleanup correctly we can't drop
migration_context before cleanup is complete:
 a) when post live migration, we move source host cleanup before
    destination cleanup(post_live_migration_at_destination will
    apply migration_context and drop it)
 b) when rollback live migration, we drop migration_context after
    rollback operations are complete

For different specific resource, we might need driver specific support,
such as vpmem. This change just ensures that new claimed specific
resources are populated to migration_context and migration_context is not
droped before cleanup is complete.

Change-Id: I44ad826f0edb39d770bb3201c675dff78154cbf3
Implements: blueprint support-live-migration-with-virtual-persistent-memory

The instance action notifications contain the user id and the
project id of the owner of the instance. However an instance
action might be initiated by another user. It could be another
user from the same project or can be an admin from the admin project.
To be able to distinguish between the user who initiated the instance
action from the user owning the instance we need to add two new
fields to the instance action notifications, action_initiator_user
and action_initiator_project

Change-Id: I649d8a27baa8840bc1bb567fef027c749c663432
Closes-bug: #1744658
Blueprint: add-action-initiator-to-instance-action-notifications

This patch refactors the sample files of instance.live_migration_rollback
notification samples to use the previously introduced common sample
data. This patch is small as the other live migration notification
transformations haven't been merged yet.

Change-Id: I834c2d5ce0257b053f7023eae55d4c9e6c9a47e1

Change-Id: Iddc5ec3b5053ddf5dce73c86edca26c4552d451b
Implements: bp versioned-notification-transformation-pike
Closes-Bug: #1684860

This patch adds bdm related data to InstancePayload. As loading BDM
can be expensive a new configuration flag 'bdms_in_notifications' is
introduced. If this is set to false (as by default) then the instance
notifications will contain 'null' value in block_devices field.
If this configuration flag is set to true then the block devices will
be loaded from the db and will be included in the notification payload.

Implements: bp additional-notification-fields-for-searchlight
Change-Id: I18e7483ec9a484a660e1d306fdc0986e1d5f952b

Add key_name field to InstancePayload which means every instance.<action>
notification now have key_name field based on the instance.key_name.

Change-Id: I39059c5077c790aa85dff6b4563f581c54536b86
Implements: bp additional-notification-fields-for-searchlight

Change-Id: Ic6cd58095cf5313325a7302a746467f57d0e0371
Implements: bp versioned-notification-transformation-pike