Show status of customer invites and allow UI option to resend invites from Customers page

Problem Definition

Currently, the status of Service Desk Customer invitations is hidden to project admins and agents. As of 3.3.0 it is possible to resend invitations by adding the customer to the service desk again, but there is not a way to see which users have accepted used the invitations or who has an expired invitation.

Suggested Solution

Add an invitation status column to the Service Desk Project -> Customers screen that would show the status of the invitation as well as allows the project admins to resend the invitation email by clicking a button or link.

Workaround

Currently you can re-add the customer and that will trigger a new invitation to the be sent, but there is simple way to see the invitation status in the UI.