Add support for on demand addon_pipeline in `/api/collect` endpoints

[keshav-space]

• /api/collect endpoint now supports optional list of addon_pipelines to run on the package. Example GET request:

  /api/collect/?purl=pkg:npm/foo@1.2.3&addon_pipelines=collect_symbols&addon_pipelines=inspect_elf_binaries

• In bulk indexing /api/collect/index_packages/ endpoint each package now also supports optional list of addon_pipelines to run on the package. Example POST request:

  {
      "packages": [
          {
              "purl": "pkg:npm/foobar",
              "vers": null,
              "source_purl": None,
              "addon_pipelines": ['inspect_elf_binaries', 'collect_symbols']
          }
      ]
      "reindex": true,
      "reindex_set": false,
  }

• fixes https://github.com/nexB/purldb/issues/376

[!note] If no addon_pipeline is provided, then only the default pipelines will be run on the package. https://github.com/nexB/purldb/blob/32ea6e810c3c371e24318440f079a7453f1c5d4a/minecode/model_utils.py#L30-L33