Return the EXACT images the user chose on their upload link.
Pass the token_id that request_image_upload_link returned. Call this after
the user says they uploaded or picked their images: it returns files[],
each with a hosted url and a source ("upload", "gallery", or "shared"), so
you place PRECISELY the images they selected instead of guessing from the
whole gallery. An empty files list means they have not chosen anything yet
-- ask them to open the link and add images, or wait and check again.
Read-only; changes nothing.
ConnectorOAuth