This includes:
- Move entity_dao.go to common since it is generic database operation
interface for all the components.
- Added `GetX` method to EntityDAO interface. It get entity that matches
provided field and value both. It is useful in case where service
lookup for database entities not based on id, name.
Signed-off-by: Akshay Gaikwad <akshay.gaikwad@rafay.co>