Writes content to the file system, using the file creation flags provided.
pub fn writeFile(dir: Dir, io: Io, options: WriteFileOptions) WriteFileError!void
pub fn writeFile(dir: Dir, io: Io, options: WriteFileOptions) WriteFileError!void {
var file = try dir.createFile(io, options.sub_path, options.flags);
defer file.close(io);
try file.writeStreamingAll(io, options.data);
}