metal: add all the files

include/renderer_mtl/objc_helper.hpp

@@ -0,0 +1,16 @@
+#pragma once
+
+#include <string>
+
+#include <Metal/Metal.hpp>
+
+namespace Metal {
+
+dispatch_data_t createDispatchData(const void* data, size_t size);
+
+} // namespace Metal
+
+// Cast from std::string to NS::String*
+inline NS::String* toNSString(const std::string& str) {
+    return NS::String::string(str.c_str(), NS::ASCIIStringEncoding);
+}