[#10514] feat(helm): Add OCI registry publishing workflow and update chart documentation

[danhuawang]

What changes were proposed in this pull request?

This PR adds support for publishing Gravitino Helm charts to OCI registry (Docker Hub) and updates documentation. The changes include:

1. GitHub Actions Workflow

   • Created .github/workflows/chart-release.yaml for automated chart publishing
   • Supports publishing all 3 charts or selective publishing
   • Includes token validation and configurable Docker repository

2. Chart Name Updates

   • Updated Chart.yaml files to include -helm suffix for OCI registry compatibility:
     • gravitino → gravitino-helm
     • gravitino-iceberg-rest-server → gravitino-iceberg-rest-server-helm
     • gravitino-lance-rest-server → gravitino-lance-rest-server-helm

3. Artifact Hub Integration

   • Added artifacthub-repo.yml metadata files to each chart directory
   • Enables automatic discovery and indexing on Artifact Hub

4. Documentation Updates

   • Updated docs/chart.md, docs/iceberg-rest-catalog-chart.md, and docs/lance-rest-server-chart.md
   • Added OCI registry installation instructions
   • Removed local chart installation methods for simplicity
   • Created README.md files in each chart directory linking to detailed documentation

Why are the changes needed?

#10514

Currently, Gravitino Helm charts are not published to any public registry, making it difficult for users to discover and install Gravitino on Kubernetes. This PR enables:

1. Easy Distribution: Users can install charts directly from OCI registry without cloning the repository
2. Version Management: Automated publishing with version control
3. Discoverability: Charts will be indexed on Artifact Hub for easy discovery
4. Simplified Installation: Standard Helm workflow using helm install oci://...

Does this PR introduce any user-facing change?

Yes. Users can now install Gravitino Helm charts directly from OCI registry:

Pull charts:

helm pull oci://registry-1.docker.io/apache/gravitino-helm --version 1.3.0
helm pull oci://registry-1.docker.io/apache/gravitino-iceberg-rest-server-helm --version 1.3.0
helm pull oci://registry-1.docker.io/apache/gravitino-lance-rest-server-helm --version 1.3.0

How was this patch tested?

After run the release chart CI, our chart is published and can be searched in Artifact Hub as following.