BUG/GUI: Properly configure slots in NestableTableView for single-entry pages

[tangkong]

Current Behavior

This is specifically for the Nestable Entry inspection pages (Collection, Snapshot)

Clicking the "open" and "remove" buttons on the NestableTableView's don't do anything

Expected Behavior

These buttons should work, and open details / remove rows as advertised

Context / environment

Raised during a dev sync meeting.

An oversight / mistake by me

Steps to Reproduce (for bugs)

1. open superscore ui or demo
2. View details for a Nestable with Nestables included (Collection / Snapshot)
3. Try clicking the delegate buttons (Open / Remove)

Suggested Solution

Open page button: Pass the open page slot to the the page and give it to the Nestable Table View

Remove Button: Implement a remove row function that modifies the held entry and removes the item from the list. Care should be taken here, and we may want to disable this row if these views are meant to be view-only.