Request access to another company's document

Files a pending request for access to a document the caller cannot see yet, and notifies the document's owner. Answers 204 with no body. 404 when the document does not exist. 409 when: the document is already public (company_document_already_public); the caller already asked and is waiting (company_document_already_requested); the caller can already reach it — owns it, holds the profile it is filed on, or has an approved share (company_document_already_shared); or any company archived it (document_request_failed, which names the archiver). The notification is best-effort: the request is recorded even if it cannot be published.