fix(helm): add OCI registry client for chart operations

[sowmya-sl]

OCI-based Helm charts were failing to install because the action configuration lacked a registry client. This change:

• Add GetDefaultOCIRegistry() to create and attach a registry client to the Helm action configuration
• Integrate registry client initialization into all Helm handlers: install, upgrade, uninstall, rollback, and chart get operations
• Add unit tests for the new registry client function

Without a registry client, operations on OCI charts (oci://) would fail with errors about missing registry support.

Fixes: HELM-611

Steps to test:

1. Create a helmrepository object in the cluster. The helmrepository object can be either cluster or namespaced, it does not matter.
2. Add repo link as https://charts.bitnami.com/bitnami . Bitnami has many OCI helm charts.
3. Once added, go to Releases and create a Helm release.
4. Sort by the newly added bitnami repository. Select nginx as the chart.
5. Click on create. Wait for the release to create and verify when created.