Add pip packaging

[scottwittenburg]

Add python packaging so users can pip install adios2. This PR follows general guidance here regarding choice of tooling and practices.

Supersedes #3949

[vicentebolea]

This is awesome! ill do a review this Monday

[scottwittenburg]

Finally success uploading a package to test.pypi.org!

After moving the PR to a branch on the main repo, I still had repeated failures to push. Some discussion around here suggested removing and re-adding the trusted publisher on the testpypi side, and when I did that, it worked! 🎉

[vicentebolea]

Great work there We are almost there, the idea looks great! As for the comments I know that this is still WIP, I just added some comments.

[vicentebolea]

Another thing to add is the badge at the readme.

[scottwittenburg]

If you download the the wheel or sdist from the artifacts of the latest "Python Packaging" build, you can see that now the version we build (the version in the .tar.gz or .whl file name) matches the version baked into the module.

[scottwittenburg]

Now each wheel undergoes an extra step where it is installed, and a simple test is run against it, e.g. here.