Added field `mix` to the options in radio-group/checkbox-group

[adinvadim]

Example:

{
    block : 'radio-group',
    mods : { theme : 'islands', size : 'm', type : 'button' },
    name : 'radio-button',
    options : [
        { val : 1, text : 'Футбол' },
        { val : 2, text : 'Баскетбол' },
        { val : 3, text : 'Гандбол' }
    ].map(item => { ...item, mix : { block : 'some-parent', elem : 'radio'  } } )
}

[belozer]

Why is that? What is the challenge?