fix(report): Refactor SBOM generation: split functions, improve PURL logic, set OS as root

[kl-sinclair]

What did you implement:

We have refactored and improved the CycloneDX SBOM generation functionality as follows:

• Refactoring: Split the GenerateCycloneDX function into ToCycloneDX, which converts a ScanResult to a CycloneDX BOM, and SerializeCycloneDX, which serializes the BOM into a byte array.
• Fix: Separated and improved functions for generating Package URLs (PURLs) from packages and libraries.
• Fix: Modified the SBOM structure so that the OS information is set as the root component.

These changes enhance the maintainability and extensibility of the codebase by modularizing the SBOM generation process and improving the handling of Package URLs.

Type of change

• Bug fix (non-breaking change which fixes an issue)

How Has This Been Tested?

$ vuls report -to-localfile -format-cyclonedx-json
or 
$ vuls report -to-localfile -format-cyclonedx-xml

before

{
  "$schema": "http://cyclonedx.org/schema/bom-1.6.schema.json",
  "bomFormat": "CycloneDX",
  "specVersion": "1.6",
  ...
  "metadata": {
    ...
    "component": {
      "bom-ref": "xxxxxxxx",
      "type": "operating-system",
      "name": "localhost"
    }
  },
  "components": [
    {
      "bom-ref": "xxxxxxxx",
      "type": "operating-system",
      "name": "macos",
      "version": "13.7.4",
      "properties": [
        {
          "name": "future-architect:vuls:Type",
          "value": "Package"
        },
        {
          "name": "RunningKernelRelease",
          "value": "22.6.0"
        }
      ]
    },
    ...
    {
      "bom-ref": "pkg:yarn/%40babel%[email protected]",
      "type": "library",
      "name": "@babel/types",
      "version": "7.26.9",
      "purl": "pkg:yarn/%40babel%[email protected]"
    },
    ...
  ],
  ...
}

after

{
  "$schema": "http://cyclonedx.org/schema/bom-1.6.schema.json",
  "bomFormat": "CycloneDX",
  "specVersion": "1.6",
  ...
  "metadata": {
    ...
    "component": {
      "bom-ref": "xxxxxxxx",
      "type": "operating-system",
      "name": "macos",
      "version": "13.7.4",
      "properties": [
        {
          "name": "future-architect:vuls:Type",
          "value": "macos"
        },
        {
          "name": "RunningKernelRelease",
          "value": "22.6.0"
        }
      ]
    }
  },
  "components": [
    ...
    {
      "bom-ref": "pkg:npm/%40babel/[email protected]",
      "type": "library",
      "name": "@babel/types",
      "version": "7.26.9",
      "purl": "pkg:npm/%40babel/[email protected]"
    },
    ...
  ],
  ...
}

Checklist:

You don't have to satisfy all of the following.

• Write tests
• Write documentation
• Check that there aren't other open pull requests for the same issue/feature
• Format your source code by make fmt
• Pass the test by make test
• Provide verification config / commands
• Enable "Allow edits from maintainers" for this PR
• Update the messages below

Is this ready for review?: YES