Do not show empty <div> elements for component items that do not render anything

Currently, the freemarker snippets rendering the containers look for example as follows:

<div${containerClass}>
  <#list hstResponseChildContentNames as childContentName>
  <div${containerItemClass}>
    <@hst.include ref="${childContentName}"/>
  </div>
  </#list>
</div>

however, it makes more sense to no show empty <div> elements outside the channel manager view is the child component has no actual rendered content.