fix(hub): add params to register_model()

[1Ayush-Petwal]

**What this PR does **:

Adds storage_key, storage_path, and service_account_name kwargs to ModelRegistryClient.register_model(). These were documented in the docstring but silently dropped — they are now forwarded to the upstream ModelRegistry.register_model().

Which issue(s) this PR fixes :

Fixes #439

Checklist:

• Docs included if any changes are user facing

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Pull request overview

Adds missing storage/auth-related kwargs to ModelRegistryClient.register_model() and forwards them to the upstream ModelRegistry.register_model() to match the existing docstring and fix silent parameter dropping (Fixes #439).

Changes:

• Extend register_model() signature to accept storage_key, storage_path, and service_account_name.
• Document the new kwargs in the docstring.
• Forward the new kwargs to the underlying ModelRegistry.register_model() call.