HUE-2132 [search] Offer field sorting within the HTML widget

Re-use the gridlayout header sorting.
Minor issue is that the list can overflow now.
[search] Subscribe to facet limit change
HUE-2128 [search] Timeline dates are not loaded properly
HUE-2165 [search] syncFields() can corrupt the model

Field that does not exist anymore should be remove in bulk in both the
collection and template field list.
New fields can be added only to the list of selected fields.
HUE-2167 [search] Solr might not always return a document
HUE-2017 [search] Warning that highlightning only works if documents have and id field

Remove the result data when switching between layouts
Happens when dropping a new HTML or Grid result widget