Add dismissed_by_security_policy field to VulnerabilityType

What does this MR do and why?

This MR adds a new field dismissed_by_security_policy to the VulnerabilityType. This new field will be used by FE to conditionally display a new badge, indicating that a vulnerability was introduced after dismissing a security policy, in the vulnerability report list.

Database query

SELECT
    security_policy_dismissals.*
FROM
    security_policy_dismissals
WHERE
    security_findings_uuids && ARRAY[ 'f4129fe1-7401-5d67-b36f-1382ca8fe06c' ]::text[];

https://postgres.ai/console/gitlab/gitlab-production-main/sessions/44010/commands/134719

References

Related to #549786

Screenshots or screen recordings

How to set up and validate locally

Follow the steps described on !206648 (merged) to dismiss a security finding in a MR.

After following these steps:

1. Merge the MR to introduce a new vulnerability
2. Go to -/graphql-explorer and use a query like:

{
  project(fullPath: "<your-project-full-path>") {
    vulnerabilities {
      nodes {
        uuid
        dismissedBySecurityPolicy
      }
    }
  }
}

MR acceptance checklist

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