[Accessibility] Capture focus via ref for RadioButtonGroup

[ShimiSun]

Expected Behavior

The RadioButtonGroup should be capable of capturing focus on the initial input radio element when targeted using ref, mirroring the behavior observed during keyboard navigation.

Actual Behavior

When employing react-hook-form or any form management tool to set focus on a specific input with an error, the RadioButtonGroup (RBG) currently lacks focusability through ref. As RBG is a Box without a tabIndex, it cannot be focused. Grommet appropriately handles a comparable scenario for keyboard navigation focus in RBG by directing focus to the first radio element. Similar behavior is expected when managing focus via ref for RBG.

URL, screen shot, or Codepen exhibiting the issue

A POC of the concept #7044
Story example

import React, { useEffect, useState } from 'react';

import { Box, RadioButtonGroup } from 'grommet';

export const myFocus = () => {
  const [value, setValue] = useState({ value: '' });

  const input = React.useRef();
  // This logic will trigger a focus on RBG when the page loads. You can notice that the focus is never set.
  useEffect(() => {
    setTimeout(() => {
      input.current?.focus();
      console.log('here', input.current);
    }, 500);
  }, []);

  const postMethods = [
    { label: 'FTP', value: 'FTP' },
    {
      label: 'File System',
      value: 'FileSystem',
    },
    {
      label: 'FTP & File System',
      value: 'FTPCopy',
    },
  ];

  // In this example there is no keyboard access to the RBG component
  // The myFocus should fix the initial focus
  return (
    <Box align="center" pad="large">
      <RadioButtonGroup
        ref={input}
        name="radio"
        options={postMethods}
        value={value}
        onChange={(event) => setValue(event.value)}
      />
    </Box>
  );
};
export default {
  title: 'Input/RadioButtonGroup/My Focus',
};

Steps to Reproduce

1. Put the story on storybook
2. Notice how the focus is not set on load, although it is triggered

Your Environment

Any

• Grommet version: latest
• Browser Name and version: Chrome 119
• Operating System and version (desktop or mobile): Mac - any