Add a link from the streamlined trust prompt to the complete item-by-item access form

When a consumer requests ongoing read access in trust mode, the owner sees the streamlined "Trust this site" prompt (RequestTrustForm): one checkbox per kind, a blanket read-trust for the whole kind. The complete, item-by-item form (RequestApproveForm) lives at a sibling route for the same request, but nothing linked to it, so an owner who would rather share specific items than trust a whole kind had no way to reach it.

Both routes (pdv.request.trust and pdv.request.approve) act on the same pdv_grant_request and gate identically, so moving between them is purely presentational, with no state to carry.

Change

• RequestTrustForm renders a "Pick specific items to share instead" link at the bottom, below the Save/Cancel actions, pointing at pdv.request.approve for the same request.
• One-directional: the complete form already nests the per-kind ongoing-access (trust) sections, so it is a superset and needs no link back.
• French translation and an owner-guide note added in the same change.