Migrate container image repository from legacy GCR syntax to native Artifact Registry

When deploying Substrate on GCP/GKE via ./hack/install-ate.sh --deploy-ate-system, the build and deployment tooling pushes images using legacy Container Registry (gcr.io) syntax configured in hack/ate-dev-env.sh.example and Makefile:

```
KO_DOCKER_REPO="gcr.io/${PROJECT_ID}/ate-images"
```
## Problem

Container Registry (gcr.io) is deprecated. When used with Google Cloud Artifact Registry's gcr.io compatibility redirect, repositories in Artifact Registry are single-level containers for packages. Path segments like ate-images/ are not subfolders, but instead get prepended into the package name (e.g. ate-images/ateapi-...), cluttering the repository.

Substrate should move to native Artifact Registry repository syntax

```${LOCATION}-docker.pkg.dev/${PROJECT_ID}/ate-images)```

## Suggested Solution
Update provisioning scripts to provision artifact registry, and update hack/ate-dev-env.sh.example and Makefile defaults to use native Artifact Registry:

```
-export KO_DOCKER_REPO="gcr.io/${PROJECT_ID}/ate-images"
+export KO_DOCKER_REPO="${GCE_REGION}-docker.pkg.dev/${PROJECT_ID}/ate-images"
```