Added missing Vector3 slerp and Vector3 project
Added missing Vector3 slerp and Vector3 project

Vector3 slerp and Vector3 project were missing from godot cpp so I added them.

GodotNativeTools/godot-cpp,godotengine/godot-cpp,GodotNativeTools/godot-cpp,GodotNativeTools/cpp_bindings,godotengine/godot-cpp,GodotNativeTools/godot-cpp,godotengine/godot-cpp,GodotNativeTools/cpp_bindings,godotengine/godot-cpp