windows/security: explicit LOAD_LIBRARY_SEARCH_SYSTEM32 for system32 dll

We recently stumpled upon dll loading issues of wtsapi32.dll with prior modification of dll search path via SetDefaultDllDirectories resulting exact same issue as in https://github.com/java-native-access/jna/pull/1614

calling LoadLibraryEx(relative_path, ..., LOAD_WITH_ALTERED_SEARCH_PATH) results in ERROR_INVALID_PARAMETER.

According to LoadLibraryEx documentation, this results in an undefined behavior when a library name is given as a relative path.
With that in mind, it would be best practise to secure system32 dll loading by using OPTION_OPEN_FLAGS set to LOAD_LIBRARY_SEARCH_SYSTEM32 for those interfaces against system32 dlls.

Map<String, Object> DEFAULT_W32SYSTEM32APIOptions = new HashMap<String, Object>(W32APIOptions.DEFAULT_OPTIONS) {{ //LOAD_LIBRARY_SEARCH_SYSTEM32 put(com.sun.jna.Library.OPTION_OPEN_FLAGS, 0x00000800); }};
Once we switched to LOAD_LIBRARY_SEARCH_SYSTEM32 all system32 dlls in use were properly found/loaded.

Start by locating W32APIOptions and the interfaces that load system32 DLLs, then inspect how OPTION_OPEN_FLAGS and LOAD_WITH_ALTERED_SEARCH_PATH are currently used. Reproduce the relative-path loading case on Windows and verify that system32 DLLs load with LOAD_LIBRARY_SEARCH_SYSTEM32 without breaking other native interfaces.