feat: Support exporting multiple actions from a single package

[kane-knowby]

The process of creating a new action is incredibly simple already, but in my view would be even better if I could group actions logically.

This makes sense especially when creating actions specific to one project, but also can work for actions published on pub.dev which might be all related.

I'm imagining it would work similarly to how the default actions are all registered together in Fluttium.

[Jochum van der Ploeg]

Hi! Thanks for opening up an issue, can you elaborate on how you would like to be able to group actions?

I think I get what you are going for but I am curious how you as a developer would want to have it shaped.