feat: Add emitForEach / emitOnEach Methods (or something similar) to Cubit

[jtdLab]

Description

When working with a Cubit that consume some other Stream you need to maintain a StreamSubscription during the life of the Cubit and close it etc. This comes with some extra work which is handled well in Bloc via emit.forEach / emit.onEach but no similar solution exists for that when using Cubit.

Desired Solution

Adding the methods emitForEach and emitOnEach with same signatures and functionality as their counter part in Emitter.

Alternatives Considered

Maybe give a Cubit its own Emitter.

[jyardin]

I think the alternative solution you proposed of exposing an Emitter would be better, as it would give a more consistent experience between Bloc and Cubit.

It would be even cooler if the Emitter is returned by an emit property, replacing the emit(State) method.
It would be a breaking change, not sure how big a breaking change though, as the main usage of emit (just calling emit(newState)) would still work as intended.

[vgtle]

This would be a great feature. Are there any plans of implementing this? Or any ways to contribute to this?