Add "Date Invoice Sent" as an option for Zoho Flow and Zoho Analtics

Add "Date Invoice Sent" as an option for Zoho Flow and Zoho Analtics

We track ar partially based on when an invoice is sent. The sent date is not available in Zoho Flow or Zoho Analytics. To get around this we have a "Date Sent" field that is manually entered right before we send the invoice.