refactor: remove dead permission_codename param from _resolve_document_ids

The keyword param was unused in the method body since an earlier commit
switched it to call permitted_document_ids(user) internally. None of the
3 call sites passed it.

Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>

src/documents/views.py

@@ -2727,7 +2727,6 @@ class DocumentSelectionMixin:
         *,
         user: User,
         validated_data: dict[str, Any],
-        permission_codename: str = "view_document",
     ) -> list[int]:
         if not validated_data.get("all", False):
             # if all is not true, just pass through the provided document ids