SMHService constructor Null safety

1. smh_flutter_sdk
2. smh_service
3. SMHService
4. SMHService constructor

SMHService class

1. Constructors
2. SMHService
3. Properties
4. baseUrl
5. dio
6. hashCode
7. hostType
8. runtimeType
9. Methods
10. configBaseHostWithEnv
11. errorFactory
12. initDio
13. noSuchMethod
14. responseFactory
15. serviceHeader
16. serviceKey
17. serviceQuery
18. setupCurrentHostEnv
19. toString
20. urlPaths
21. Operators
22. operator ==