The `JupyterExtensionIntegration.install()` is invoking the incorrect installer from the Jupyter extension

[tonybaloney]

Steps to reproduce

1. Open a workspace with a poetry environment
2. Make sure the ipykernel package is not installed
3. Open a jupyter notebook
4. On prompt to install ipykernel select yes

Expected

poetry add --dev is invoked

Actual

It invokes pip install -U instead of poetry add --dev

This applies to main/latest

I also noticed there is no unit/integration test for JupyterExtensionIntegration

[tonybaloney]

this is the root cause. The DataScienceInstaller does not care about Pipenv or poetry environments, it defaults back to pip

https://github.com/microsoft/vscode-python/blob/main/src/client/common/installer/productInstaller.ts#L474-L487

[karthiknadig]

/cc @DonJayamanne @joyceerhl