BlockNote outputs default styles on save

If you edit and save a page without making any change, the output XWiki syntax contains a bunch of CSS styles:

• for paragraphs and headings:

  (% style="color:default;background-color:default;text-align:left" %)
  

• for images:

  data-xwiki-image-style-alignment="start"
  

Ideally BlockNote shouldn't output default styles (that have not been applied explicitly by the user). If that's not possible, then we need to try to filter them out on save.