Shortcut to set heading in markdown cells

[rchiodo]

Discussed in https://github.com/microsoft/vscode-jupyter/discussions/10769

^{Originally posted by RafalSkolasinski July 11, 2022} In normal Jupyter Notebook or Jupyter Lab one can hit

<ESC> + <number = 1, 2, 3, 4, etcr>

to set e.g. top level or second level heading.

This seems to be missing from the VS Code when working with notebooks. It is a major impact to my flow :(