feat: add clientset for DLRover

[zhengxle]

What changes were proposed in this pull request?

This PR introduces a generated typed clientset, along with informers and listers, for the DLRover elasticjob resource (v1alpha1).

Specifically, the following components were added:

• Clientset: Located in go/elasticjob/client/clientset. Provides a type-safe way to interact with ElasticJob resources.
• Informers & Listers: Added to support efficient resource caching and event-driven controller logic.
• API Registration: Included register.go and doc.go in go/elasticjob/api/v1alpha1 to ensure proper scheme registration.
• Added hack/update-codegen.sh: A professional-grade utility script to automate the generation of DeepCopy, Clientset, Listers, and Informers.

Why are the changes needed?

• Resolves manifests: generate clientset/listers/informers into pkg/client package #1164: This PR formally provides the implementation for the requirement proposed in manifests: generate clientset/listers/informers into pkg/client package #1164.
• Production Proven (Joint Collaboration): This implementation has been jointly integrated and verified by MetaX (沐曦) and Zhejiang Lab (之江实验室). It is currently being used within the Nanhu Scheduling System for large-scale distributed training orchestration on MetaX GPU clusters.
• Improved DX: Enables type-safe resource manipulation and prevents runtime errors associated with dynamic clients.

Does this PR introduce any user-facing change?

Yes (for developers). Users can now utilize the typed clientset to interact with ElasticJob resources.

How was this patch tested?

• In-situ Validation: Successfully tested and deployed within the Zhejiang Lab infrastructure.
• Compilation Check: Passed go build ./client/clientset/... and go mod tidy against the latest upstream master in the go/elasticjob directory.

[zhengxle]

Hi @BalaBalaYi @workingloong, this PR introduces the typed clientset which has been verified in production at Zhejiang Lab with MetaX GPUs. Could you please help to approve the workflow and review the changes? Thanks!