Add unit tests for DeploymentToCloneSet

[GautamBytes]

What's in this PR?

This pull request introduces a comprehensive unit test suite for the DeploymentToCloneSet conversion function located in pkg/conversion/cloneset_convertion.go.

Key Contributions

• Complete Coverage: Adds tests to ensure all fields in the conversion function are correctly mapped, including metadata (labels, annotations, finalizers) and spec fields (replicas, selector, template, revisionHistoryLimit, minReadySeconds).
• Update Strategy Validation: Verifies that the updateStrategy fields (paused, maxUnavailable, maxSurge) are correctly populated from the deployment's rolling update configuration.
• Edge Case Handling: Includes specific tests for edge cases to ensure robustness, such as:
  • Zero-value inputs (replicas: 0)
  • Nil and empty fields (e.g., nil rollingUpdate configuration)

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[GautamBytes]

@furykerry @hantmac please take a look!