Draft: POC allow excluding packages MRAP

What does this MR do and why?

Related to: #494722

MR acceptance checklist

Please evaluate this MR against the MR acceptance checklist. It helps you analyze changes to reduce risks in quality, performance, reliability, security, and maintainability.

Screenshots or screen recordings

Before	After

How to set up and validate locally

1. Create a new project
2. Add an empty Gemfile.lock file
3. Add a file called gl-sbom-gem-bundler.cdx.json with the content

{
    "bomFormat": "CycloneDX",
    "specVersion": "1.4",
    "serialNumber": "urn:uuid:a15e529c-2113-4a11-a694-6bc3ea4e2b53",
    "version": 1,
    "metadata": {
        "timestamp": "2022-02-23T08:02:39Z",
        "tools": [
            {
                "vendor": "GitLab",
                "name": "Gemnasium",
                "version": "2.34.0"
            }
        ],
        "authors": [
            {
                "name": "GitLab",
                "email": "support@gitlab.com"
            }
        ],
        "properties": [
            {
                "name": "gitlab:dependency_scanning:input_file:path",
                "value": "Gemfile.lock"
            },
            {
                "name": "gitlab:dependency_scanning:package_manager:name",
                "value": "bundler"
            },
            {
                "name": "gitlab:meta:schema_version",
                "value": "1"
            }
        ]
    },
    "components": [
        {
            "name": "sidekiq",
            "version": "4.2.10",
            "purl": "pkg:gem/sidekiq@4.2.10",
            "type": "library",
            "bom-ref": "pkg:gem/sidekiq@4.2.10",
            "licenses": [
                {
                    "license": {
                        "name": "Custom-License"
                    }
                }
            ]
        }
    ]
}

3. Add a .gitlab-ci.yml with the content

include:
  - template: Jobs/Dependency-Scanning.gitlab-ci.yml

gemnasium-dependency_scanning:
  stage: test
  script: 'pwd'
  artifacts:
    reports:
      cyclonedx: gl-sbom-gem-bundler.cdx.json

6. Go to Build > Pipelines
7. Click on the last pipeline
8. Click on the Licenses tab
9. Verify the license for the sidekiq was detected
10. Go to Secure > Policies
11. Click in New policy
12. Select Merge request approval policy
13. Change to the yaml mode and copy the policy content below:

type: approval_policy
name: abcd
description: ''
enabled: true
rules:
  - type: license_finding
    match_on_inclusion_license: true
    license_types:
      - LGPL-3.0
    license_states:
      - detected
    branches: []
    licenses:
      denied:
        - name: LGPL-3.0
          packages:
            excluding:
              - name: sidekiq
actions:
  - type: require_approval
    approvals_required: 1
    role_approvers:
      - maintainer
  - type: send_bot_message
    enabled: true
approval_settings:
  block_branch_modification: true
  prevent_pushing_and_force_pushing: true
  prevent_approval_by_author: true
  prevent_approval_by_commit_author: true
  remove_approvals_with_new_commit: true
  require_password_to_approve: false
fallback_behavior:
  fail: closed

14. Click in configure with a merge request
15. Merge the policy
16. Create an MR modifying the README file
17. Verify that MR is not blocked