[GCP Artifact Registry] Support notifications for GCP Artifact Registry

[mzueva]

Background For local docker registry new tools are automatically registered using DockerRegistryController.notifyDockerRegistryEvents API method (it is possible to configure a hook that will be called on any docker registry event. GCP Artifactory also provides a was to receive notifications from push events: https://cloud.google.com/artifact-registry/docs/configure-notifications

Approach Check notification approach suggested by GCP https://cloud.google.com/artifact-registry/docs/configure-notifications and investigate if it is possible to used it for platform deployed in GCP.