Overhaul setup/build to enable one-step install?

[hugetim]

Echo kernel uses Hatch to install the kernel when 'pip install' is run rather than requiring a separate "install.py" to be run after 'pip install'. It shouldn't be too hard to make 'nbstata's installation similarly smooth.

Hmm, but then how would we still allow the user to choose where the kernel is installed? https://hugetim.github.io/nbstata/user_guide.html#install-nbstata