Add UI Validity Check for MR Modal

What does this MR do and why?

This MR is using the FF introduced in this MR, so it needs to be merged first > Worker service populate token statuses for mr p... (!198831 - merged)

This MR adds validity check section with the token badge - UI only. The token status is hard coded. API integration will be done in a follow-up MR.

Configuration	MR Modal
	No validity check
FF: false

References

Screenshots or screen recordings

Before	After

How to set up and validate locally

1. Enable FF: validity_checks_security_finding_status http://gdk.test:3000/rails/features/validity_refresh
2. Enable FF: validity_checks http://gdk.test:3000/rails/features/validity_checks
3. Enable validity checks: https://docs.gitlab.com/user/application_security/vulnerabilities/validity_check/#enable-validity-checks
4. Clone this project: https://gitlab.com/gitlab-org/govern/threat-insights-demos/verify-validity-refresh-check
5. Run a successful pipeline
6. Create a new MR, similar to this > https://gitlab.com/gitlab-org/secure/tests/secret-detection-test-projects/validity-checks/validity-checks-token-states/-/merge_requests/1
7. This should generate vulnerabilities that you can open a MR modal

Note: The token status is hardcoded. It will be integrated with the DB value in another MR

MR acceptance checklist

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

Related to #537751 (closed)