Partner and Staff Sign Off #307

Currently, when a staff goes to sign off on items, only the staff is required to sign.

We want to add the feature to allow the partner to sign as well. Incorporate this in the frontend modal by adding an additional section below the current section, with a Partner Name text field where the user can type in there name, and a partner signature box, just like the staff signature box. See attached image.

This will require schema changes to the SignOff object. We now also want to store the partner signatureUrl, as well as the printed partner's name (signerName). Ensure that the partner signature gets properly stored in the azure database.

On the front end, we now want to be able to preview staff signature and partner signature. Add another hover text like what we already have, but for the partner signature. This will need to be implemented on the shipments tab and the sign-offs tab. See attached image.