This is based on top of !6526, will mark ready after !6526 is merged.
-- v2: propsys: Support converting to BSTR for PropVariantToVariant. propsys: Fix a crash in tracing for VariantToPropVariant. propsys: Implement PropVariantToBSTR. propsys: Use msvcrt wide string functions. propsys/tests: Test truncating for PropVariantToString. propsys/tests: Test PropVariantToBSTR. propsys: Add PropVariantToBSTR stub.