Refactor `SyncLicenseScanningRulesService`

We want to identify possible improvements to SyncLicenseScanningRulesService and implement them.

---

The following discussion from !147561 (merged) should be addressed:

• @bauerdominic started a discussion: (+1 comment)

  @mcavoj I haven't fully reviewed this yet 🙂 SyncLicenseScanningRulesService has become quite complex and it mixes data structures with processing logic. WDYT about a follow-up to refactor the service? Something along:

  class LicensePolicyData
    attr_reader :scan_result_policy_read, :project
  
    def initialize(scan_result_policy_read, project)
      @scan_result_policy_read = scan_result_policy_read
      @project = project
    end
  
    def license_policies
      # ...
    end
  end
  
  class LicenseReportData
    attr_reader :report, :target_branch_report
  
    def initialize(report, target_branch_report)
      @report = report
      @target_branch_report = target_branch_report
    end
  
    # ...
  end
  
  class LicenseViolationChecker
    def initialize(license_policy_data, license_report_data)
      @license_policy_data = license_policy_data
      @license_report_data = license_report_data
    end
  
    def violates_policy?
      # ...
    end
  end
  
  class SyncLicenseScanningRulesService
    # ...
  
    private
  
    def violates_policy?(merge_request, rule, violations)
      policy_data = LicensePolicyData.new(rule.scan_result_policy_read, project)
      report_data = LicenseReportData.new(report, target_branch_report(merge_request))
      checker = LicenseViolationChecker.new(policy_data, report_data)
      violation = checker.violates_policy?
      save_violation_data(violations, rule, violation.denied_licenses_with_dependencies) if violation
      violation
    end
  
    # ...
  end