Implement snapshot operations

This adds the various commands corresponding to the new snasphot
methods.

blueprint stack-snapshot
Co-Authored-By: ala.rezmerita@cloudwatt.com

Change-Id: I8803c54c5cd76700f1591c8d28650bf60a2f5167
Implement restore operation

This adds new methods to manage snapshot restoration.

blueprint stack-snapshot
Co-Authored-By: ala.rezmerita@cloudwatt.com

Change-Id: I917c5d89f586110c0614e05e134bebde27d4db55
Merge "Implement snapshot operations"
Merge "Implement restore operation"