Add support for the metricsGcpServiceAccountEmail field in ConfigManagement Fleet-level default config

Author: terlar

mmv1/products/gkehub2/Feature.yaml

@@ -283,6 +283,9 @@ properties:
               - name: 'preventDrift'
                 type: Boolean
                 description: 'Set to true to enable the Config Sync admission webhook to prevent drifts. If set to `false`, disables the Config Sync admission webhook and does not prevent drifts.'
+              - name: 'metricsGcpServiceAccountEmail'
+                type: String
+                description: 'The Email of the Google Cloud Service Account (GSA) used for exporting Config Sync metrics to Cloud Monitoring. The GSA should have the Monitoring Metric Writer(roles/monitoring.metricWriter) IAM role. The Kubernetes ServiceAccount `default` in the namespace `config-management-monitoring` should be bound to the GSA.'
               - name: 'git'
                 type: NestedObject
                 description: 'Git repo configuration for the cluster'