Add some ComboBox aka TypeAhead to the headless components

[ghost]

We lack some very important headless component, that we should add to our foundation: A ComboBox or TypeAhead (see also headless-ui

This element is used to select one or many items from some "large" list of elements; could be static or generated from dynamic remote queries on the fly during typing.

We should investigate, how to manage (display and unselect) multiple selections. If there is some senseful headless approach, we should use that for the ListBox and our DataCollection as well. (might be a different issue of course)