Provide two modes for component rendering: Standalone or complete

(1) standalone means: Only some specific HstComponent plus its descendants get their doBeforeRender called & their render (template)
(2) not standalone mean: All HstComponents of the entire page get their doBeforeRender called but only some specific component + its descendants gets its renderer (template) called.

Also note that we should include a facility method for (2) to check whether the doBeforeRender is part of the tree of components below the 'component render' : If not, a developer might want to shortcircuit the doBeforeRender for performance reasons