Add container scanning for registry banner

What does this MR do and why?

Add container scanning for registry banner

• Add to vulnerability report page

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

Screenshots are required for UI changes, and strongly recommended for all other merge requests.

Before	After

How to set up and validate locally

In rails console:

Feature.enable(:container_scanning_for_registry)

1. Import the https://gitlab.com/gitlab-examples/security/security-reports project or any project that generates vulnerabilities
2. Run pipeline, generate vulnerabilities
3. Navigate to the Vulnerability Report page
4. Click on container registry vulnerabilties tab
5. Observe empty state
6. Navigate to the security configuration page
7. Toggle ON Container Scanning For Registry
8. Navigate to the Vulnerability Report page
9. click on container registry vulnerabilties tab
10. Observe alert banner, refresh page confirm it persists
11. Dismiss banner, refresh page, confirm banner is gone
12. Table OK to render empty since the demo project doesn't currently generate vulns, that has been tested seperately in prior MRs

Numbered steps to set up and validate the change are strongly suggested.

Related to #444883 (closed)