Support for passing nbconvert preprocessor

[nishikantparmariam]

Context

I have a use case to apply custom transformation on notebooks - add / remove cells, change content of cells etc. It would be great to have a feature that allows me to pass a custom preprocessor that will be ran before building JupyterBook.

Please let me know if there are workarounds for the same.

Related Issue : https://github.com/executablebooks/MyST-NB/issues/360

Proposal

• Adding an entry point that allows passing nbconvert preprocessor either through _config.yml file or Jupyterbook's build CLI.
• As a first step in the build process, all the notebooks should be passed through the preprocessor(s) provided.

Tasks and updates

No response