[macOS] Switch Angle to Metal backend.

Author: bruvzg

platform/macos/gl_manager_macos_angle.mm

@@ -48,7 +48,7 @@
 Vector<EGLAttrib> GLManagerANGLE_MacOS::_get_platform_display_attributes() const {
 	Vector<EGLAttrib> ret;
 	ret.push_back(EGL_PLATFORM_ANGLE_TYPE_ANGLE);
-	ret.push_back(EGL_PLATFORM_ANGLE_TYPE_OPENGL_ANGLE);
+	ret.push_back(EGL_PLATFORM_ANGLE_TYPE_METAL_ANGLE);
 	ret.push_back(EGL_NONE);
 
 	return ret;