[FR]: Allow custom validation handlers for `Authenticator` input events

### On which framework/platform would you like to see this feature implemented?

React, React Native

### Which UI component is this feature-request for?

Authenticator

### Please describe your feature-request in detail.

In the React and React Native `Authenticator` components users should be able to add custom validation handlers to input events via a React idiomatic API.

### Please describe a solution you'd like.

_No response_

### We love contributors! Is this something you'd be interested in working on?

- [X] 👋 I may be able to implement this feature request.
- [X] ⚠️ This feature might incur a breaking change.