Cleanup: forbid implicit copy and move for multi function

This avoids accidental copies/moves which are never really intentional.

Pull Request: https://projects.blender.org/blender/blender/pulls/110168

source/blender/functions/FN_multi_function.hh

@@ -39,7 +39,7 @@
 
 namespace blender::fn::multi_function {
 
-class MultiFunction {
+class MultiFunction : NonCopyable, NonMovable {
  private:
   const Signature *signature_ref_ = nullptr;