stack abandon should have a dry run option

[JunJie Nan]

To display the abandon data only, without deleting the stack.

Below is a usage scenario:
1. heat stack-abandon stack --dry-run > stack.data,
2. heat stack-update ...
3. If update failure found, we can run heat stack-adopt -a stack.data to adopt back.

Current behavior(delete stack and show abandon data) does not make sense. So no chance left to end users to keep a healthy stack data before update. And right after stack abandon to do stack adopt is too heavy.

[OpenStack Infra (hudson-openstack)]

Fix proposed to branch: master
Review: https://review.openstack.org/84664

[OpenStack Infra (hudson-openstack)]

Fix proposed to branch: master
Review: https://review.openstack.org/84680

[Steven Hardy (shardy)]

https://review.openstack.org/#/c/84664/ is marked WIP so bumping to J3

[Zane Bitter (zaneb)]

I think *every* abandon needs to be a "dry run" in the sense of not deleting the stack, as discussed in bug 1353670 (which I raised because I didn't know about this one).

Do we still need a --preview option (which I guess would return the data without changing the state) if abandon is implemented like that?

[OpenStack Infra (hudson-openstack)]

Change abandoned by Angus Salkeld (<email address hidden>) on branch: master
Review: https://review.openstack.org/84680
Reason: adandoning old reviews, feel free to repost this if you want to get it merged.

[OpenStack Infra (hudson-openstack)]

Change abandoned by Steve Baker (<email address hidden>) on branch: master
Review: https://review.openstack.org/84664
Reason: This is being handled now by https://review.openstack.org/#/c/181880