Allow ApprovedInvoices to be marked as paid

There is going to be a separate resource for this at the backend. On UI side it probably goes through the table. You would hit some button (**Mark as paid**) on the invoice row. Provided the query gets accepted, it would then remove it from the table (moves onto **Paid Invoices** one) and update its state.

Start by tracing the Approved Invoices table and the actions available on each invoice row. The issue describes a Mark as paid button that sends the accepted request to the separate backend resource, removes the invoice from this table, moves it to Paid Invoices, and updates its state; completion is verified by that workflow.

Written by the indexing model from the issue text.