[facet js] fix reordering of facet check boxes. Closes #2732947
Before this patch, when one select an element, it's moved to the top of
the select content. Fine. But when it's later deselected, it stays there
instead of moving back to its original location.
This patch fixes that by introducing a facetCheckBoxReorder function which
properly reorder the whole facet, instead of buggy attempt to locally reorder.
