use bulk advisories endpoint instead of quick audit endpoint, if available

[isaacs]

Not available on the public registry yet, but will be at /-/npm/v1/security/advisories/bulk. Can test against the internal staging server for now. POST a JSON body like: '{"handlebars":["4.7.0","1.2.3","4.7.1"],"kind-of":["6.0.1"],"minimist":["0.2.0","1.0.2"]}' and it'll return {"handlebars": [...advisories], ...}