Signed documents in the host's check-in email

Visitor flows can now send signed documents to internal recipients. Under Visitor flow > Notifications, admins can attach all signed PDFs to the flow's notification emails, and to the host's check-in email if the host gets notifications by email. If the PDFs total more than 7 MB, the email links to the dashboard instead. Both switches are off by default, so admins need to turn them on.