Improvements in reportFormat JSON for errors during processing

[surendrapathak]

When --reportFormat is JSON, we must ensure:

1. Output is a valid JSON
2. Score is set to 0 if there are any internal or processing errors.
3. An error string is populated with any necessary error strings.

I recommend following changes:

  "run_id": "e6468750-1506-42ff-b635-16068fdcdb27",
  "timestamp": "2023-02-27T20:37:11Z",
  "creation_info": {
    "name": "sbomqs",
    "version": "v0.0.7",
    "scoring_engine_version": "2"
  },
  "files": [
    {
      "file_name": "sboms/trivy-0.36.1_alpine-3.17.2.spdx.json",
      "spec": "", # Cannot be filled
      "spec_version": "", # Cannot be filled
      "file_format": "json",
      "avg_score": 0,
      "error": "Error processing file: Invalid SBOM"
   }```