We need a new mechanism to support the ability for developers to define a
logical group for selectOneRadio components.

selectOneRadio components that are assigned to the same logical group will
affect each others state as follows:

  1. Only one selectOneRadio component can be selected at one time in a logical
group.

  2. Selecting a selectOneRadio component will automatically deselect any
previously selected selectOneRadio component in the same logical group.

This mechanism will make it possible to have multiple logical groupings of
selecOneRadio components on the same page, whereas today all selectOneRadio
components interact with each other on the same page, which is very limiting.

This concept is similar to the logical grouping of valid target
panelPositionable components so we should ensure that the mechanism used to
define the member groups in both cases is consistent.