Feature to delete docker images with `@google-cloud/artifact-registry`

Hi, according to the [Artifact Registry](https://cloud.google.com/artifact-registry/docs/repositories/delete-repos#gcloud) and [Artifact Registry Client](https://cloud.google.com/nodejs/docs/reference/artifact-registry/latest/artifact-registry/v1.artifactregistryclient) documentation, there is no way to delete docker images via the NodeJS API.

**Is your feature request related to a problem? Please describe.**
I understand that [gcloud](https://cloud.google.com/sdk/gcloud/reference/artifacts/docker/images/delete) can be used, however I would like my application to be able to delete docker images when a related project is deleted in Firebase Firestore.

**Describe the solution you'd like**
New `deleteImage` commands for docker images.

**Describe alternatives you've considered**
I have tried using [deletePackage](https://cloud.google.com/nodejs/docs/reference/artifact-registry/latest/artifact-registry/v1.artifactregistryclient#_google_cloud_artifact_registry_v1_ArtifactRegistryClient_deletePackage_member_1_) but it doesn't seem to work.