Show the list of resources scanned by DAST in pipelines' security dashboard - Backend

Implement the backend work for #197115 (closed)

We want to show an alert to summarize the various reports results in pipelines' security tab.

Design

Requirements

• Expose the data required for the frontend to render the additional info the dropdowns.
  • Data to be exposed:
    • A list of enabled report types, with the total count of detected vulnerabilities for each of them.
    • If DAST is enabled, we want to expose the scanned resources count as well (based off prior work to display this information in MR widget: backend !28718 (merged) & frontend !26825 (merged)). We won't be needing the CI job's URL at this stage but it might be worth including it anyways since we will most like display it in a future iteration.

Availability & Testing

Links / references

• frontend issue: #214387 (closed)
• Parent issue: Show the list of resources scanned by DAST in pipelines' security dashboard
• Original issue: Show the list of resources scanned by DAST