Refactor code for copy volume to image using TaskFlow 0.1

Registered by Abhishek Kekane

Refacttor the copy_volume_to_image code to use TaskFlow (https://wiki.openstack.org/wiki/TaskFlow).
Split copy_volume_to_image code into tasks that perform the individual required actions to accomplish the pieces desired outcome.

Blueprint information

Status:
Complete
Approver:
John Griffith
Priority:
Low
Drafter:
None
Direction:
Needs approval
Assignee:
Abhijeet Malawade
Definition:
Obsolete
Series goal:
Accepted for future
Implementation:
Not started
Milestone target:
milestone icon next
Completed by
Sean McGinnis

Related branches

Sprints

Whiteboard

We will submit three patches as below to accomplish our goal:
1. copy volume to image api flow : (review in progress)
2. copy volume to image manager flow : (review in progress)
3. call api flow and manager flow to execute task using taskflow library : (work in progress)

Gerrit topic: https://review.openstack.org/#q,topic:bp/copy-volume-to-image-task-flow,n,z

Addressed by: https://review.openstack.org/69320
    Tasks for api flow of Copy volume to image api

Addressed by: https://review.openstack.org/69329
    Tasks for manager flow of Copy volume to image api

<jdg>
I'm deferring moving any more API calls to taskflow. We've moved create_volume to taskflow and I think we still have a long way to go before realizing the benefits here and I'd like to get at least one API task figured out and solid before migrating everything. The taskflow implementation adds quite a bit of code and complexity that I want to make sure is worth the investment.

(?)

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