Add flow support for all selectors spec files #67
Description
Describe the problem:
As of now the scaffold does not provide flow support for the jest spec files of reselect selectors. The reason why we haven't added it in the first place was that the selector is typed with the global StateType of the application, and the tests only provide a subset of it since it would otherwise increase the maintainability of the tests into nowhere.
A possible solution would be to either add a } | Object to the global StateType declaration, but this solution would also lead to less feedback from flow in the real world usage.