Add `LOAD_LIBRARY_SEARCH_SYSTEM32` support

[`LoadLibraryExA`](https://learn.microsoft.com/en-us/windows/win32/api/libloaderapi/nf-libloaderapi-loadlibraryexa) has many flags that would be nice to use.  Transmuting handles to minidl::Library s "works", but is a little awkward, and skips the super useful error handling code as well.