[How to] Resize component externally

- [x] I have searched [existing issues](https://github.com/facebook/litho/issues) and this is not a duplicate

## Version
0.32

## Issues and Steps to Reproduce
So here is the use case that we're trying to resolve in my team.

We need to use a dynamically resized `WebView` that talks through our app with a `@JavascriptInterface` annotated methods. Basically when the content changes, it is recalculated and invokes a method `setHeight` and we're intercepting it. Then we change the `WebView` height and update the view.

After migrating to Litho we are not sure how can it be done. The `JavascriptInterface` object is passed as a prop to the `WebViewSpec` (`@MountSpec`). From there, I don't think there are any options to do the trick:
- dynamic props are a no-go, because we cannot update state from them (`@OnBindDynamicValue`) cannot have `ComponentContext` in it's parameters
- State can be updated only from other Litho components

So the only way I know of is recreating the components using different `@Props`, but there's no way to identify which Litho component actually called the method.

## Expected Behavior
We want to pass new properties from _outside_ to one of our components. Can this be done in any way?