List contacts

The account's address book, auto-fed by mail traffic: correspondents, message counts, last activity, and notes. Most recently active first by default (order=recent), for display: a contact that gets new mail during a paged scan moves ahead of the cursor, so that scan can skip it. To sync the whole book, pass order=created: oldest first by creation time then id, a key that never changes, so every contact that exists for the whole scan comes back exactly once and contacts created meanwhile come at the end. A cursor only continues the order it came from (400 INVALID_CURSOR otherwise). Aggregates data from every mailbox, so mailbox-confined tokens are denied (400 MAILBOX_CONFINED).