Subclass/Superclass facet-query improvements

[ThomasThelen]

@zilongliu-geo noted that one optimization we can make is by querying for the top-level class when all subclasses are selected. In 1.2.1, when users select the superclass of a facet (typically in a check-box type facet like Hazards)-all of the subclasses are expanded out and placed in the query.

For example, if you select the Fire facet-all of the children are placed in the query using VALUES while we could just use the Fire class. Some basic query testing shows that in this case, searching for the Fire superclass is ~1 second faster than a search using all its subclasses.