[EditorEvent] Add events for when a window opens

[badandbest]

What can't you do?

We have an editor event for when the preferences window is opened but that's about it.

I think it would be useful. For example you'd be able to add your own pages to the project settings.

How would you like it to work?

I don't know if there should be a different event for every main widget? ( i.e editor.settings, editor.inspector, editor.hierarchy, editor.console ).

If not that, then maybe qt.open or window.open. It would still be nice to narrow the search to a specific window.

The event should pass the window as an argument.

What have you tried?

I couldn't think of a good way to detect when a window opens. If there is please let me know.

Additional context

No response