Support validation directive for radio group

We have this wonderful validation directive > https://gitlab.com/gitlab-org/gitlab/blob/35a069ae43f54577632b6d7f8bb9cc8125445b87/app/assets/javascripts/vue_shared/directives/validation.js#L1

Unfortunately, at this time it doesn't support radio groups:

// currently this doesn't work

<gl-form-radio-group
        v-model="form.fields.visibility.value"
        v-validation:[form.showValidation]
        data-testid="fork-visibility-radio-group"
        name="visibility"
        required
      >

Well, let's change this and ensure our validation directive can support radio group 🙌

More info

The following discussion from !55838 (merged) should be addressed:

• @dpisek started a discussion:

  question: unfortunately the validation directive doesn't work on gl-form-radio-group, as it needs to be added to an actual form element (input, select, etc.) but here it would receive a div. You would see something like this in the console:

  

  That's because a div technically can't have a name attribute.