Refactors the Makefile venv handling logic to be simpler, by leveraging pipenv more to populate path variables.
Runs pipenv lock when the Pipfile is newer than Pipfile.lock.
Makes PYTHON_DIST_DIR configurable.
Refactors python/dist to handle the case when setup.py and Pipfile are in separate directories by creating symlinks. requirement*.txt files are now only generated if Pipfile changes.
This PR:
pipenv lockwhen thePipfileis newer thanPipfile.lock.PYTHON_DIST_DIRconfigurable.python/distto handle the case whensetup.pyandPipfileare in separate directories by creating symlinks.requirement*.txtfiles are now only generated ifPipfilechanges.python/dist.