Persist license policy violations data

What does this MR do and why?

This MR refactors and extends SyncLicenseScanningRulesService to persist violated license names.

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.

How to set up and validate locally

1. Create a project
2. In rails console, enable feature flag:

   Feature.enable(:save_policy_violation_data, Project.last)

3. Add CI configuration:

   include:
     - template: Jobs/Dependency-Scanning.gitlab-ci.yml
   
   build-job:
     script:
       - echo "Compiling the code..."
       - echo "Compile complete."

4. Add empty requirements.txt file
5. Go to Secure -> Policies and create a new policy:

   type: approval_policy
   name: Licenses
   description: ''
   enabled: true
   rules:
     - type: license_finding
       match_on_inclusion: true
       license_types:
         - BSD 3-Clause "New" or "Revised" License
         - GNU Lesser General Public License v3.0 or later
         - MIT License
       license_states:
         - newly_detected
       branch_type: protected
   actions:
     - type: require_approval
       approvals_required: 1
       role_approvers:
         - developer

6. Create MR adding a new package that would violate the policy. Example:

   diff --git a/requirements.txt b/requirements.txt
   index 8b137891791fe96927ad78e64b0aad7bded08bdc..3ac9d3235031db76d721f145fbeb3849c5c5df54 100644
   --- a/requirements.txt
     +++ b/requirements.txt
     @@ -1 +1 @@
   -
     +pluggy==1.1.0

7. After the pipeline completes, verify that jobs pass, artifacts are present and approvals are required
8. In rails console, check that violations_data have been persisted (e.g. {"violations"=>{"licenses"=>["MIT License"]}}):

   MergeRequest.last.scan_result_policy_violations

Related to #433401 (closed)