Cannot scroll window in notebooks using `zz`, `zt` and `zb`

[jackos]

Describe the bug Hotkeys such as:

• zz
• zt
• zb

Do not work using the native VSCode notebooks

To Reproduce Steps to reproduce the behavior:

1. Create a Jupyter notebook .ipynb
2. Make a few cells that fill up more than a screen
3. Try to scroll the window using zz, zt or zb, nothing works

• Extension (VsCodeVim) version: 1.20.3
• VSCode version: 1.56.2
• OS: Windows

Additional context See VSCode locking out the ability to use Vim keybindings that recenter the window, I demonstrate how it works on a normal file, then show it not working in a notebook:

https://user-images.githubusercontent.com/77730378/119208643-c6244c00-bad5-11eb-9b60-fa8e6ef72150.mp4