Fix hardcoded Maya style navigation pan key modifier

ALT key modifier was hardcoded is node_3d_editor_plugin.cpp and didn't take editor settings into account.

Fix #46973

(cherry picked from commit 31077d875ea9f778d960d9bdfbc6affbab54081a)

editor/plugins/spatial_editor_plugin.cpp

@@ -1847,10 +1847,8 @@ void SpatialEditorViewport::_sinput(const Ref<InputEvent> &p_event) {
 
 		} else if (m->get_button_mask() & BUTTON_MASK_MIDDLE) {
 
+			const int mod = _get_key_modifier(m);
 			if (nav_scheme == NAVIGATION_GODOT) {
-
-				const int mod = _get_key_modifier(m);
-
 				if (mod == _get_key_modifier_setting("editors/3d/navigation/pan_modifier")) {
 					nav_mode = NAVIGATION_PAN;
 				} else if (mod == _get_key_modifier_setting("editors/3d/navigation/zoom_modifier")) {
@@ -1861,8 +1859,9 @@ void SpatialEditorViewport::_sinput(const Ref<InputEvent> &p_event) {
 				}
 
 			} else if (nav_scheme == NAVIGATION_MAYA) {
-				if (m->get_alt())
+				if (mod == _get_key_modifier_setting("editors/3d/navigation/pan_modifier")) {
 					nav_mode = NAVIGATION_PAN;
+				}
 			}
 
 		} else if (EditorSettings::get_singleton()->get("editors/3d/navigation/emulate_3_button_mouse")) {