Add unit tests for getViewer function

[GautamBytes]

What this PR does / why we need it:

This PR introduces comprehensive unit tests for the getViewer function in the polymorphichelpers package. The tests ensure that the function correctly returns a TablePrinter for all supported Kruise resource types and returns the expected error for unsupported types.

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[GautamBytes]

@hantmac please take a look at this pr and other test prs whenever feasible!