Ability to filter and weight by record source

[andrewpollock]

(more generally I think that the problem is that OSV consumers can be a bit overzealous in that everything is treated as "vulnerability" without vetting anything. Maybe there should be a way to say that some entries are generated based on automated tools and should be vetted. If they are confirmed by maintainers consumers can be confident that entries are vulnerabilities. I proposed "confidence" in another context google/osv.dev#918 but it can probably be applied here)

Originally posted by @evverx in google/osv.dev#2176 (comment)