List per-user ACL grants on a folder.

Returns all direct user ACL grants on the folder (DVT-1421). Requires share:manage on the folder — the owner, org admin, or a user with an acl-admin grant may call this. A non-owner editor (ACL editor) cannot list grants; only share-capable principals can. Unlike dashboards/sheets/skills, a folder has no visibility of its own (every active org member can see the folder tree), so an unauthorized same-org caller is refused with 403, not 404; a cross-tenant caller still gets 404 (the folder doesn't exist in their org). In the Snowflake native app, ownership and acl-admin grants are ignored for callers whose live tier is viewer.