Need to initialize AttributeFields with link destinations specified

Right now we're creating the initial AttributeFields for an account based on the original ``.yml files, which don't include the types of pages to link to. Instead, we're inferring those page types from the old-style links/relations.

Before we can remove those relations (and associated tables, etc), we'll need to add the those link destinations to all of the default field specs -- and we should probably just use those to create new-style links upon initialization.

Start by locating the account initialization path that creates AttributeFields and the default field specifications represented by the original .yml files. Compare those specifications with the old-style links/relations, then verify that every default destination is included and that initialization creates new-style links before the legacy relations are removed.

Written by the indexing model from the issue text.