add forStepClass method to get state more convenient

[bangnokia]

Hi,

This forStepClass is similar to the forStep method to get the state for a specific step, but it uses a component class, which is not the component name. So it could be easy to autocomplete by the IDE, or in case we have many component registries in a package for long names like package:namespace.feature.steps.options-step.

And by the way the name of the Step component registered in the service provider is used nowhere in view, so sometimes it could leak to an error when trying to refactor the class component, tho.

This is an addition, so there is no breaking change

[freekmurze]

Seems like the tests are failing could you take a look?

Could you also document this?

[bangnokia]

yes, let me check and update the pull request, the tests failed to seem weird because I didn't modify anything

[bangnokia]

I added the doc for this method and also updated the snapshot for the test

[freekmurze]

Thanks!