feat: add helm chart for training-operator

[vicoooo26]

What this PR does / why we need it:

Add a Helm chart for deploying the training-operator on Kubernetes. The chart includes all necessary CRDs (TFJob, PyTorchJob, JAXJob, MPIJob, PaddleJob, XGBoostJob), RBAC resources, cert-manager integration, webhook configuration, and configurable values for production deployments.

Which issue(s) this PR fixes (optional, in Fixes #<issue number>, #<issue number>, ... format, will close the issue(s) when PR gets merged):

Checklist:

• Docs included if any changes are user facing

[github-actions]

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