[macOS] Fix Maya navigation with ALT + mouse scroll

Methods were being called with InputEventMouseMotion instead of InputEventPanGesture, and they were null.

Fixes godotengine/godot#16181 on the master branch

(cherry picked from commit 394a7826be11db83762036d2de2c8b7df0c8962e)

editor/plugins/spatial_editor_plugin.cpp

@@ -1948,22 +1948,22 @@ void SpatialEditorViewport::_sinput(const Ref<InputEvent> &p_event) {
 
 		switch (nav_mode) {
 			case NAVIGATION_PAN: {
-				_nav_pan(m, pan_gesture->get_delta());
+				_nav_pan(pan_gesture, pan_gesture->get_delta());
 
 			} break;
 
 			case NAVIGATION_ZOOM: {
-				_nav_zoom(m, pan_gesture->get_delta());
+				_nav_zoom(pan_gesture, pan_gesture->get_delta());
 
 			} break;
 
 			case NAVIGATION_ORBIT: {
-				_nav_orbit(m, pan_gesture->get_delta());
+				_nav_orbit(pan_gesture, pan_gesture->get_delta());
 
 			} break;
 
 			case NAVIGATION_LOOK: {
-				_nav_look(m, pan_gesture->get_delta());
+				_nav_look(pan_gesture, pan_gesture->get_delta());
 
 			} break;