added alot more keybings to the notebook editor

[jonah-iden]

What it does

This adds multiple new keybindings and some commands and preferences to the notebook editor that vscode supports as well:

• ctrl+x cut cell

• ctrl+c copy cell

• ctrl+v paste cell

• Enter (new for code cells) focus editor

• Esc unfocus editor/stop markdown edit

• linenumber preference to activate and deactivate line numbers in cell editors

• collapse/expand cell ouptut command

How to test

Open a notebook and test the new commands

Follow-ups

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]

Alright, looks good to me after the latest changes 👍