Add buffer size attribute/struct for FindFirstFileEx family

[morganbr]

The FindFirstFileEx family of functions (FindFirstFileExW, FindFirstFileExA, FindFirstFileExFromAppW, FindFirstFileTransactedA, FindFirstFileTransactedW) all have an out void* lpFindFileData parameter where the size and structure of the buffer written is documented to be based on the fInfoLevelId enum parameter (documented at https://learn.microsoft.com/en-us/windows/win32/api/minwinbase/ne-minwinbase-findex_info_levels). However, both values of that enum have the same result of writing a WIN32_FIND_DATA (there are A and W versions). The SAL annotations also acknowledge this -- for example FindFirstFileExW is annotated _Out_writes_bytes_(sizeof(WIN32_FIND_DATAW)) LPVOID lpFindFileData.

Ideally the type for lpFindFileData could change to WIN32_FIND_DATA for the greatest clarity, but if not, annotating it with NativeArrayInfoAttribute would help with marshaling.