The setup.py has been deprecated in Python for quite a while, and it has
been generating a lot of warnings. We can avoid it completely, together
with the shell call, by calling the babel functions directly.
I'm also moving the extractor settings from pyproject.toml to the
relevant babel-*.cfg files, to keep everything together.
Signed-off-by: Radomir Dopieralski <openstack@dopieralski.pl>
Change-Id: Ie0616b5f2a96cf8560135e5f6849c737aa9b88d0