Drp `poetrylock` and `pyproject` mandatory arguments
without default values and drops `src` from `mkPoetryPyhon`.
Fix test invocations with invalid arguments.
- Extract utility functions to ./lib.nix
- Extract buildPythonPackage to ./mk-poetry-dep.nix
- Replace some functions with existing builtin functions
- Use lib.partition for python package splitting
- Drop package filtering on the top-level and leave it to pep425.nix
Provides a `select` function that picks the most appropriate `.whl` file
based on platform, arch, python version and manylinux/OSX - version.
- Adds unit tests for pep425
- Adds test for manylinux support
- Fixes overrides: `passhtru` must be extended, not overwritten
- Don't strip python packages: this screws up manylinux binaries
