Create ncrystal-tests package

[tkittel]

It would be super useful if we could have a special package (on pypi most likely) which would be able to test any NCrystal installation, be it manually installed, installed via conda, or whatnot. Preferably, it would simply glob up as many parts of /tests as possible.

Even if this was just the pure python scripts tests, it would already be a useful addition to the capabilities, somewhere in between nctool --test and the full CTests.

In a way, this would be similar to the ATLAS KitValidation release, back in the days.

[tkittel]

mockup:

pip install ncrystal-tests
ncrystal-test-installation

[tkittel]

Presumably, the ncrystal-tests package would have a strict pinning on the ncrystal version, although it should be done in a way which does not preclude usage in a manually installed setup. Perhaps the pinning would be in an optional dependency? pip install ncrystal-testkit[compatversion] ??