Fixed notebook editor staying current even when selecting sidebar or bottom panel

[jonah-iden]

What it does

This lets the current notebook editor stay as active in the plugin host even when selecting another widget as long as the notebook-editor is visible and no other text-editor is selected

How to test

you can find an vscoed extension here which adds an output channel to show the cahnge events. See that the active notebook editor and cell editor should stay even when selecting another non text-editor widget.

Follow-ups

This still has the same issues as the text editor active handling. For example having a text or notebook editor open and a custom editor right beside it so both are visible, then focusing the custom editor does not change the vscode api activeTextEditor or ActiveNotebookEditor

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

[msujew]

Looks good to me, thanks 👍