Move that rendering up a higher level.

- Apply this to the rest as we desire unicode output for all cells when
  possible.
Changelog.
Fix up workspace safe_html rendering

- Due to the different expected links between images and anchors, a set
  of xpath rules need to be applied to get the targets updated with what
  users probably intend to display - images are linked to the raw form
  and the relative anchor targets are linked to the file.

Fixes: tracker item 3525