Move `form` element into `section.widget` [story:56545568]

* make `section.widget` be a direct child of `.widget-area`, rather than
  of `form.import`, since every other widget works this way, and
  DashboardController expects it
Merge pull request #316 from reciprocity/feature/fix-import-pages

Recent JS changes broke import; this fixes it
Remove abstract from edit modal and supress some metadata warnings