Opens a directory at the given path. The directory is a system resource that remains
open until close is called on the result.
The directory cannot be iterated unless the iterate option is set to true.
On Windows, sub_path should be encoded as WTF-8.
On WASI, sub_path should be encoded as valid UTF-8.
On other platforms, sub_path is an opaque sequence of bytes with no particular encoding.
pub fn openDir(dir: Dir, io: Io, sub_path: []const u8, options: OpenOptions) OpenError!Dir
pub fn openDir(dir: Dir, io: Io, sub_path: []const u8, options: OpenOptions) OpenError!Dir {
return io.vtable.dirOpenDir(io.userdata, dir, sub_path, options);
}