Proposal: Create a bridge between redux-form and react-final-form

Hey there @erikras!

I know there is quite the burden of having to support both `redux-form` and this in parallel, and not only does it take up a lot of time for you, but it's got to be stressful!

So this is more of a feature/suggestion ticket. What if you created a small bridge library between the two as a solution for people's migration woes?

Since the `final-form` has very similar fields, what if you created an easy monkeypatch/decorator to add a config prop to `redux-form`?

Something like:

```
export default reduxForm({
form: 'myCoolForm',
finalForm: true
})(connect(mapStateToProps, mapDispatchToProps)(MyCoolFormComponent));
```
and this would route the logic to `final-form` (you'd have to use the `final-form` fields still)

This would probably trigger most people to migrate very easily, and create an opt-in path to cherry pick situations where they want to still use `redux-form`.

Just a thought! Thanks for all your hard work! :-)

### Are you submitting a **bug report** or a **feature request**?

Feature request + suggestion to help you!

No files, tests, or entry points are named. Start by reviewing the proposed migration relationship between redux-form and react-final-form, then clarify the bridge API, compatibility boundaries, and acceptance criteria with maintainers. Done would require an agreed design and validated migration path.

Written by the indexing model from the issue text.