Build a cross Python version conda package

[fabiencelier]

At the moment we release one Conda package per OS and per Python version (while we have one wheel per OS but cross Python versions.)

It would be nice to manage to release only one Conda package per OS so we don't have to do new releases when there are new Python versions.

The difficulties are in conda build. When building the package, the Python files always end up in the folder of a pinned Python version such as "lib/python3.8/site-packages".

Here is a discussion about it.

A possible solution would be to release 2 Conda packages:

• jdk4py-bin which is OS dependent, containing all the java runtime without any Python code.
• jdk4py which is a noarch package importing jdk4py-bin and exposing it as a Python library.