SupportsShouldProcess doesn't care for WhatIfPreference

Summary of the new feature
It seems the SupportShouldProcess rule doesn't always pick up WhatIf being passed to a function later on. It mostly does this for external modules (that do it properly), but not when the functions are within the same module (different files) that I am actually building.

Proposed technical implementation details (optional)
I guess a prescan should be made and if there are commands with explicit WhatIf calls or WhatIfPreference calls it should treat it as condition to ignore.

首先重现 SupportsShouldProcess 的行为，测试在同一模块中的函数之间传递 WhatIfPreference，然后检查 SupportsShouldProcess 规则及其对模块边界的处理。完成标准是：同一模块中的函数显式使用 WhatIf 或 WhatIfPreference 时能够始终如一地被识别，且不会产生误报。