[Bug] RadioButtonGroup attached properties need setters

[davidbritch]

Description

The RadioButtonGroup class has GroupName and SelectedValue attached properties. However, both lack setters which makes setting them through code less obvious.

Basic Information

• Version with issue: 5.0-pre1

Workaround

Use BindableObject.SetValue() to set the attached properties, e.g.:

            StackLayout fruitStackLayout = new StackLayout
            {
                Children = { appleRadioButton, bananaRadioButton, pineappleRadioButton, otherFruitRadioButton }
            };
            fruitStackLayout.SetValue(RadioButtonGroup.GroupNameProperty, "fruits");