Make URLs of submission pages consistent

[nstz0]

https://vgmdb.net/album/{id}/edit (no change) https://vgmdb.net/album/new (no change) https://vgmdb.net/db/artists-submit.php?do=edit&id={id} -> https://vgmdb.net/artist/{id}/edit https://vgmdb.net/db/org-submit.php?do=edit&id={id} -> https://vgmdb.net/org/{id}/edit https://vgmdb.net/db/product-submit.php?do=edit&id={id} -> https://vgmdb.net/product/{id}/edit https://vgmdb.net/db/release-submit.php?do=edit&id={id} -> https://vgmdb.net/release/{id}/edit https://vgmdb.net/db/event-submit.php?do=edit&id={id} -> https://vgmdb.net/event/{id}/edit https://vgmdb.net/db/artists-submit.php -> https://vgmdb.net/artist/new https://vgmdb.net/db/org-submit.php -> https://vgmdb.net/org/new https://vgmdb.net/db/product-submit.php -> https://vgmdb.net/product/new https://vgmdb.net/db/event-submit.php -> https://vgmdb.net/event/new