Add option to provide a callback function to focusOnFirstError

[Fronix]

Reasons for making this change

fixes #3580

Focusing the first error using focusOnFirstError requires an actual element to be focusable. This is not always possible, you might have disabled fields that are filled by some type of action that the user has missed.

This change provides the option to add a custom callback function to focusOnFirstError, the function recieves a RJSFValidationError in which you can handle what happens then focusOnFirstError is called.

Example:

import { RJSFSchema, RJSFValidationError } from '@rjsf/utils';

const schema: RJSFSchema = {
  type: 'string',
};

const focusOnError = (error: RJSFValidationError) => {
  console.log('I need to handle focusing this error');
};

render(<Form schema={schema} focusOnFirstError={focusOnError} />, document.getElementById('app'));

Checklist

• I'm updating documentation
  • I've checked the rendering of the Markdown text I've added
• I'm adding or updating code
  • I've added and/or updated tests. I've run npm run test:update to update snapshots, if needed.
  • I've updated docs if needed
  • I've updated the changelog with a description of the PR
• I'm adding a new feature
  • I've updated the playground with an example use of the feature

[Fronix]

Not sure but it could be better to just provide the entire error array here. Though this would change the definition of onFirstError.

[heath-freenome]

yes, that would change the definition.