This is based on top of !6526, will mark ready after !6526 is merged.
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v9: propsys: Support converting to BSTR for PropVariantToVariant.
propsys: Use debugstr_variant for the trace in VariantToPropVariant.
propsys: Implement PropVariantToBSTR.
propsys/tests: Test truncating for PropVariantToString.
propsys/tests: Test PropVariantToBSTR.
propsys: Add PropVariantToBSTR stub.
https://gitlab.winehq.org/wine/wine/-/merge_requests/6640