Include jlpm within this package (Issue #15)

[cronan03]

Fixes #15

[fcollonval]

To fix the linter, you can change the .pre-commit-config.yaml file to exclude yarn.js:

for example

   - repo: https://github.com/codespell-project/codespell
     rev: "v2.2.6"
     hooks:
       - id: codespell
         args: ["-L", "sur,nd"]
+        exclude: jupyter_builder/yarn.js

[fcollonval]

Oki I missed that you added the javascript source files within this PR... Could you create another branch for that? This is a good example of why creating multiple branches is a good practice to avoid mixing up various subjects and making it simpler to fix the CI 😉