TemplateData is refactored to make it possible
- split SubGraph and ScenarioData from TemplateData
- build entity index and relationship index in TemplateData
- delay variable extraction to subgraph build
- simplify the process of adding scenario to repository
Implement: blueprint entity-equivalence
Change-Id: I7192e3a82880dc3c3995000c029af4e0aabd8d6c