Add purls for binary classifiers

[noqcks]

I noticed that purls were empty for binary matched packages

  {
      "id": "42128c6f2809fa6c",
      "name": "go",
      "version": "1.19.4",
      "type": "binary",
      "foundBy": "binary-cataloger",
      ...
      "purl": "",
      ...
  },

And after

  {
     "id": "42128c6f2809fa6c",
     "name": "go",
     "version": "1.19.4",
     "type": "binary",
     "foundBy": "binary-cataloger",
     ...
     "purl": "pkg:generic/go@1.19.4",
     ...
  },

Reference: purl-spec generic type

cc: @kzantow

[kzantow]

Good catch!