Add or Update Draft Pre-closing Documents

Adds draft pre-closing documents to a closing or updates their document type if it has changed since their last addition. After successful completion of this request, the document references that were added to this closing will have a closingDesignation of DRAFT_PRE_CLOSING and a sourceType of LENDER. In addition, any pre-closing document references with a sourceType of LENDER that were previously sent to the settlement agent using the POST close/closings/{id}/pre-closing-documents/send endpoint will be automatically duplicated with a closingDesignation of DRAFT_PRE_CLOSING.