Extend documentation on how to set up the virtual environment #31342
Description
In #30371 a minimal documentation on how to set up the virtual environment using pipenv is added.
This should be expanded to also include plain python -m venv and virtualenv (20.x).
Moreover, it would be good to describe the different ways to create an in-place installation.
CC: @mkoeppe
Component: documentation
Issue created by migration from https://trac.sagemath.org/ticket/31342