Move the donate-form pages to the new layout template

Building on !37 (closed), this moves monthly-giving, champions-of-privacy, and the root contents.lr to the new layout. All three had to be moved at once because they all use the same model (donate-form). There aren't actually 15 changes here, 8e7b852d is just part of !37 (closed) and can be removed in a rebase.

Blocked by !37 (closed) and lego!22 (merged)