Make CheckButtonGroup and similar selectors accept Parameterized objects as options

[CesarRodriguezPereira]

When dealing with selectors in panel, there's non uniform behaviour depending on what selector you're using.

As per the documentation, there's "a broad category of multi-value, option-selection widgets that provide a compatible API and include the MultiSelect, CrossSelector, CheckBoxGroup and CheckButtonGroup widgets". However, out of these widgets, 2 accept Param objects and 2 don't.

Both MultiSelect and CrossSelector accept param.Parameterized obects as options, labeling them as "ClassName instance.name", and returning the list of selected objects when calling ".value". However, CheckBoxGroup and CheckButtonGroup don't accept these objects as inputs, as they expect an element of List(String). This makes it so you can only use the names of objects directly when using these selectors, thus not having the entire object readily at your disposal when using them.

I think making CheckBoxGroup and CheckButtonGroup behave like MultiSelect already does would be great, affording users more flexibility on what to select, and providing uniformity to an API that's already documented as compatible.