Add `radiogroup` role to the `KRadioButtonGroup`

[MisRob]

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Desired behavior

Add radiogroup role to the KRadioButtonGroup component as described in https://www.w3.org/WAI/ARIA/apg/patterns/radio/

The Value Add

@radinamatic:

This role offers a better UX to screen reader users by providing context that they are navigating through (and selecting from) a group of related set of options, and how many they have available.

References

• https://github.com/learningequality/kolibri/pull/12751#issuecomment-2477835851

[iamshobhraj]

@MisRob I'll be happy to take up this task.

[MisRob]

Thanks @iamshobhraj, assigned!