PR Summary

Refactor IsNullLike() to evaluate the most commonly-expected null-like values first.

New order of evaluation:

1. IsNull(value):
   1. value == null
   2. value == AutomationNull.Value
2. value == DBNull.Value
3. value == AutomationNull.Value

PR Context

IsNullLike() is used in binders like -eq (e.g., $null -eq $value) and it makes the most sense to evaluate in order of the most common null/null-like values first so that the code path short-circuits in the most common situations.

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