Add form names (without pokemon_name) for missing languages.

Notes:

- Unown, Arceus, and Genesect are just given names like "One form" in
  X/Y.  I consulted Pokédex 3D Pro for Unown and Arceus, and named
  Genesect's forms after their drives (since they don't have official
  names).

- Names for Spiky-eared Pichu are missing, since it's missing from X/Y
  and Pokédex 3D Pro.

- Korean names for Arceus are missing; we have type names, but I don't
  know how to say "____ type", or whether it would be better to just
  use the type name like the French and German localizers for Pokédex
  3D Pro did.

- Eternal Floette is just "Éternelle" in the French text file, rather
  than "Fleur Éternelle", but I think that's silly so I ignored it.

  It does raise the question of whether I should really have typed
  "Floette Éternel" though — the official convention seems to be
  "Pokémon species names are masculine, even for all-female species",
  but... they seem not to be going with that here, possibly because
  this is a specific Floette?  Or, more likely, because they just
  didn't think about it that hard.