Get Google Cloud Artifact Registry artifact details

What does this MR do and why?

This MR implements the new GraphQL query googleCloudArtifactRegistryRepositoryArtifactDetails to retrieve the Google Cloud Artifact Registry artifact's details.

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How to set up and validate locally

query getGarArtifactDetails {
  googleCloudArtifactRegistryRepositoryArtifact(
    googleCloudProjectId: "dev-gcp-s3c-integrati-9abafed1"
    location: "us-east1"
    repository: "demo"
    image: "app@sha256:2d89cf02221901640a7bd7369f88d031631e05e593f7a3789275c1a253106c17"
    projectPath: "gitlab-org/gitlab-test"
  ) {
    ... on GoogleCloudArtifactRegistryDockerImageDetails {
      name
      uri
      tags
      imageSizeBytes
      uploadTime
      mediaType
      buildTime
      updateTime
      projectId
      location
      repository
      image
      digest
      artifactRegistryImageUrl
    }
  }
}

Related to #425150 (closed)