Add image filtering for vulnerabilities graphql query

What does this MR do and why?

Addresses #338669 (closed)

In order to add dropdown filters for image in issue #337882 (closed), we need to support image filter in the GraphQL query.

image is specific to cluster_image_scanning or container_scanning report type. Because of which, when the image field is given, the report_type filter if it's given will be ignored and cluster_image_scanning report_type is applied implicitly.

Screenshots or screen recordings

Without Filter:

With Image Filter:

How to set up and validate locally

GraphQL Query

query{
  project(fullPath: "root/security-reports") {
    vulnerabilities(image:"registry.gitlab.com/gitlab-org/security-products/dast/webgoat-8.0@sha256:bc09fe2e0721dfaeee79364115aeedf2174cce0947b9ae5fe7c33312ee019a4e") {
      nodes {
        title
      	severity
        reportType
      	location {
            __typename
            ... on VulnerabilityLocationContainerScanning {
                image
          }
        }
      }
    }
  }
}

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