Self-serve payments for unpaid invoices

Customers who have unpaid invoices due to a payment failure will now receive an email with a link to make a payment. The payment link will also appear for that invoice in the invoices page in the Billing area on the Mux dashboard. This allows customers to rectify late or delinquent invoices when there is an issue with their method of payment without needing to contact Mux support for a payment link.