Request Invoicing: Improve the decryption user experience on the Invoice Dashboard

[MantisClone]

Problem

The Invoice Dashboard takes a long time to load for users who have a large number of encrypted invoices. This is because, after #335, it waits until all encrypted invoices are decrypted before displaying the first page.

Possible Solutions

• Display encrypted invoices before they're decrypted.
  • Requires Retrieve encrypted requests without decrypting them. Decrypt later. requestNetwork#1534
• Decrypt them one-at-a-time in the background. Update table rows to show the decrypted data as it becomes available.
• Add (i) icon next to filtering selectors and sort carrots with tooltips explaining that "filtering / sorting is disabled until all requests are decrypted"
• Display an error toast if the user clicks on sorting or filtering before all requests are decrypted. Explain "Cannot sort/filter until all requests are decrypted".
• Display a progress bar to show how long until all requests are decrypted. Assume all requests take the same amount of time to decrypt.