Generate pyi for pyluxcore

[Pyrolistical]

Python pyi file should be provide along side so/dylib/pyd files to provide typing information. This would make pyluxcore more self documenting.

I tried mypy's stubgen, but the output is pretty bad

There is probably a smarter way to directly generate pyluxcore.pyi from https://github.com/LuxCoreRender/LuxCore/blob/master/src/luxcore/pyluxcore.cpp

In the worse case a pyluxcore.pyi could be hand maintained.

[Pyrolistical]

Could use https://github.com/boostorg/python/issues/277