Implement cases for pipenv and poetry module installers for the DataScienceInstaller

[tonybaloney]

Fixes #16615

There are 4 module installers:

    serviceManager.addSingleton<IModuleInstaller>(IModuleInstaller, CondaInstaller);
    serviceManager.addSingleton<IModuleInstaller>(IModuleInstaller, PipInstaller);
    serviceManager.addSingleton<IModuleInstaller>(IModuleInstaller, PipEnvInstaller);
    serviceManager.addSingleton<IModuleInstaller>(IModuleInstaller, PoetryInstaller);

I noticed that the names of the Pipenv and poetry installers are constants, so I've imported those constant values instead of hardcoding the string (like it is with the Pip string)

[joyceerhl]

FWIW, I believe the data science team intentionally only implemented support for installing via pip and conda, under the assumption that data science packages like jupyter and tensorboard aren't generally installed as project dependencies and don't need to be managed through poetry and pipenv (at least, I remember discussing this with @DonJayamanne when I was implementing TensorBoard integration for the Python extension earlier this year). See: #11717

[tonybaloney]

Both the Pipenv and Poetry installers are run with the --dev flag, so its not installed as a project dependency. These are the installers that are run for any other VS Code dependency, black, pylint, autopep8. The current behaviour is inconsistent with the how the Python extension handles missing packages for its own purposes.

Also, running pip within a poetry environment will work, but it puts the lock file out of sync and causes other issues.

[joyceerhl]

Tagging the data science engineers as FYI since I believe our team owns the data science-specific parts of the Python extension codebase 😊

[IanMatthewHuff]

LGTM from data science side. Final signoff should be from the Python folks though.

[tonybaloney]

@kimadeline can you review for the Python extension team please

[kimadeline]

[kimadeline]

@tonybaloney PR looks good, please fix the TypeScript tests and we can merge it afterwards.

[tonybaloney]

@kimadeline oops. fixed it.