Style: Enforce separation line between function definitions

I couldn't find a tool that enforces it, so I went the manual route:
```
find -name "thirdparty" -prune \
  -o -name "*.cpp" -o -name "*.h" -o -name "*.m" -o -name "*.mm" \
  -o -name "*.glsl" > files
perl -0777 -pi -e 's/\n}\n([^#])/\n}\n\n\1/g' $(cat files)
misc/scripts/fix_style.sh -c
```

This adds a newline after all `}` on the first column, unless they
are followed by `#` (typically `#endif`). This leads to having lots
of places with two lines between function/class definitions, but
clang-format then fixes it as we enforce max one line of separation.

This doesn't fix potential occurrences of function definitions which
are indented (e.g. for a helper class defined in a .cpp), but it's
better than nothing. Also can't be made to run easily on CI/hooks so
we'll have to be careful with new code.

Part of #33027.

editor/editor_folding.cpp

@@ -127,6 +127,7 @@ void EditorFolding::_fill_folds(const Node *p_root, const Node *p_node, Array &p
 		_fill_folds(p_root, p_node->get_child(i), p_folds, resource_folds, nodes_folded, resources);
 	}
 }
+
 void EditorFolding::save_scene_folding(const Node *p_scene, const String &p_path) {
 	ERR_FAIL_NULL(p_scene);
 
@@ -150,6 +151,7 @@ void EditorFolding::save_scene_folding(const Node *p_scene, const String &p_path
 	file = EditorSettings::get_singleton()->get_project_settings_dir().plus_file(file);
 	config->save(file);
 }
+
 void EditorFolding::load_scene_folding(Node *p_scene, const String &p_path) {
 	Ref<ConfigFile> config;
 	config.instance();