Refactor npm audit producer

[ptzianos]

Issue

When the npm audit producer was written, advisories would be hosted by NPM itself. The reports produced by the npm audit command would include links that would point to an NPM page with the advisory. However, that is no longer the case. The reports now include links that point to Github hosted advisories and the Github API is quite different than the NPM one. The NPM links can still be used, but they will immediately redirect to the Github Advisory page. Furthermore, the response generated by NPM to a request for the JSON document of the advisory isn't, some 301 response, but instead it's a 200 page with the text Redirecting in the body, a header saying that the response is JSON and the location header set to the Github advisory page. The npm audit producer needs to be refactored to be able to fetch the Github Advisories.

Expected behaviour

The npm audit report should be parsed correctly and advisories should be fetched without issues from Github

Actual behaviour

Advisory fetching fails

Steps to reproduce

Run the producer for any report

[linear]

OCU-14 Refactor NPM audit consumer