EngineModel constructor Null safety

1. irte_engine
2. engine_model.interface
3. EngineModel
4. EngineModel constructor

EngineModel class

1. Constructors
2. EngineModel
3. Properties
4. hashCode
5. runtimeType
6. Methods
7. copyWith
8. noSuchMethod
9. toJson
10. toString
11. Operators
12. operator ==