cdac: Fix GetModuleMetaDataFileInfo null-param handling and output initialization

[Copilot]

GetModuleMetaDataFileInfo was checking for null pointer params inside the try block (throwing NullReferenceException instead of returning E_POINTER) and initializing output pointers inside the try block, leaving them uninitialized on exception paths before the assignments.

• Return HResults.E_POINTER immediately for any null pointer param, before the try block — matching the pattern of CreateHeapWalk, UnwindStackWalkFrame, and other APIs in the file
• Move *pResult = FALSE, *dwTimeStamp = 0, *dwImageSize = 0 initializations before the try block so callers always observe defined values on failure paths

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