HTML export options for types

[jefferyshivers]

Export separate full annotations list divs for each type (or in groups) with an option like

\setOption scholarly.annotate.export.html.by-group
  #`(
     (((class . "annotations")
       (id . "first-group")) 
                              . critical-remark)
     (((class . "annotations")
       (id . "another-group"))
                              . (musical-issue lilypond-issue))
  )

With CSS, one could put each group in a column. I think that concept was already discussed somewhere, but this is one (perhaps of several?) way to implement that. This way the list(s) could be uniquely sorted (in addition to the preexisting sorting options for reordering).