Do not (re)store state of Open Editors

[colin-grant-work]

What it does

Removes state restoration for Open Editors widget. Because tree nodes in the Open Editors widget include a reference to a widget, they were triggering double state restoration for all editor widgets in the application. Since the state of the Open Editors widget is entirely derived, there's no need to store or restore it.

How to test

1. Start the application.
2. Open and close editors.
3. The Open Editors widget should behave normally.

Review checklist

• As an author, I have thoroughly tested my changes and carefully followed the review guidelines

Reminder for reviewers

• As a reviewer, I agree to behave in accordance with the review guidelines

[vince-fugnitto]

I confirm the changes work as expected 👍
The open-editors are properly updated when editors are opened, and are restored (not by state) when the application is started.