feat: implement lock-file satisfiability with pypi dependencies (#494)

This PR adds support for checking the satisfiability of the lock-file
which includes pypi-dependencies.

Purls have been added to the lock-file
(conda/rattler#414) (See also:
conda/ceps#63). This enables checking
which conda packages will install which pypi packages without needing to
check the internet. This ensures we can still check if a lock-file is up
to date quickly.

I did not profile this code but I think there are a lot of places we can
improve the performance. Thats for a later PR.

I also didn't add tests. I think we should but we can also do that in
another PR.

Closes #467

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Co-authored-by: Ruben Arts <[email protected]>