Assignees - Final Response

When an assignment workflow is complete users want to, by default, see just a summarized "final answer" with any final versions of attachments, instead of having to read through the entire history of responses to know where it landed and what is current.

This feature would introduce an ability for the closing user to provide a "final response", they would enter the response and upload attachments just like any other responder using the same interface components @apps/nextjs/src/app/_components/Vulcan/FormRenderer/core/components/Inputs/FormAssigneeInput/AssigneeList/ResponseRows/ResponseRow.tsx, but their response would be flagged with a special "isFinal" (or similar) property. Piggybacking on the recent work to allow the final approver to reject a response, we want this final response to add a new node to the end of the workflow.

When the AssigneesList component @apps/nextjs/src/app/_components/Vulcan/FormRenderer/core/components/Inputs/FormAssigneeInput/AssigneeList/index.tsx builds the timeline of responses, if the value of the input is closed (isClosed = true) and it finds a response marked "isFinal" it will display only the final response instead of the full timeline. There should be a button to "show history" similar to how we have "Show More" / "Show Less" on the history right now. That "Show History" button should be permissioned only to those who have Edit permissions on the form.

The closing user should also have an alternative option of selecting an existing response to promote with the "isFInal" flag, if someone else has already provided a response that is satisfactory. In this case no new node would be created in the workflow. In either case (new final response or promotion of previous response) the action will close the workflow. Only one response may have the "isFinal" flag at any time.

MER-329