Add support for alternative virtual environment generators in faag-cli app generation

[pythonhubdev]

Description

Currently, the faag-cli tool supports virtual environment generation using poetry. However, some users prefer to use other virtual environment generators like venv and pipenv. Adding support for these alternative generators would increase the flexibility of the faag-cli tool and allow users to choose their preferred method for installing packages and creating virtual environments.

For example, a user could run the following command to generate a Flask app with pipenv as the virtual environment generator:

faag generate --type flask --name env_app --installer pipenv

By default, the poetry installer would be used, but users would have the option to specify an alternative installer if they choose.

Proposed Changes

Add support for alternative virtual environment generators in the faag-cli tool, allowing users to choose their preferred method for installing packages and creating virtual environments.

Additional Context

This feature would increase the versatility of the faag-cli tool and make it more accessible to users who prefer alternative virtual environment generators to poetry.