Adding python purl identifiers

[noqcks]

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[captn3m0]

A few notes (for this and similar PRs):

1. I haven't actually seen generic used in the wild. Unless we have a real usecase for it, lets not add it.
2. Most of the official repository ones will get picked up by repology. While not inaccurate to add them now, its probably better to spend your time on product coverage (how many products have PURL+repology identifiers), instead of PURL coverage itself.
3. Try to add references to other types as well, importantly the ones that won't get picked up from repology. Things like docker (official images, and popular unofficial images, such as bitnami ones), and direct links to github/source code. See the consul.md file for eg.

[noqcks]

1. For the generic type, I see syft is using it for matching binaries. The real world use I came upon was golang, which is a binary installed directly from a tar.gz. I made a PR over there to add more purl coverage for binary matching (Add purls for binary classifiers anchore/syft#1435). I think this is a valid use case for the generic type? But maybe that's a better discussion for the syft repo.

2. Yep noted. I was doing some manual exploration of syft output for various installs, including Python. And noticed that the purl identifiers were quite unique and decided to throw them here. Feel free to merge or close, I know these should be covered by repology.

[captn3m0]

Could you add dockerhub references, and we can merge it after that.

[captn3m0]

Syft binary matching seems to have improved! Last I remember, it wasn't using purls, but this is nice.

Just have to be careful about clashes if we use generic, but here looks good 👍🏽