PR Summary

Tracking issue: #12631.

Replace #14189

We never check for null in the WriteDebug() API until low level host implementations where we ignore null messages.
For WriteError() we throw if null.
For WriteObject() we accept null.
For WriteProgress() we throw if null.
For WriteVerbose we accept null (we do the same as for WriteDebug()).
For WriteWarning we accept null (we do the same as for WriteDebug()).
For WriteCommandDetail() we accept null.

For ShouldProcess and ShouldContinue - it is all about formatting output and .Net format methods accepts nulls.

PR Context

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