Use a PackedStringArray for the "open in new inspector" editor setting

This is safer and provides a more convenient array editor for users.

editor/editor_node.cpp

@@ -6172,7 +6172,14 @@ EditorNode::EditorNode() {
 	EDITOR_DEF("interface/inspector/horizontal_vector2_editing", false);
 	EDITOR_DEF("interface/inspector/horizontal_vector_types_editing", true);
 	EDITOR_DEF("interface/inspector/open_resources_in_current_inspector", true);
-	EDITOR_DEF("interface/inspector/resources_to_open_in_new_inspector", "Script,MeshLibrary");
+
+	PackedStringArray open_in_new_inspector_defaults;
+	// Required for the script editor to work.
+	open_in_new_inspector_defaults.push_back("Script");
+	// Required for the GridMap editor to work.
+	open_in_new_inspector_defaults.push_back("MeshLibrary");
+	EDITOR_DEF("interface/inspector/resources_to_open_in_new_inspector", open_in_new_inspector_defaults);
+
 	EDITOR_DEF("interface/inspector/default_color_picker_mode", 0);
 	EditorSettings::get_singleton()->add_property_hint(PropertyInfo(Variant::INT, "interface/inspector/default_color_picker_mode", PROPERTY_HINT_ENUM, "RGB,HSV,RAW,OKHSL", PROPERTY_USAGE_DEFAULT));
 	EDITOR_DEF("interface/inspector/default_color_picker_shape", (int32_t)ColorPicker::SHAPE_OKHSL_CIRCLE);

editor/editor_properties.cpp

@@ -4356,11 +4356,11 @@ EditorProperty *EditorInspectorDefaultPlugin::get_editor_for_property(Object *p_
 				editor->setup(p_object, p_path, p_hint == PROPERTY_HINT_RESOURCE_TYPE ? p_hint_text : "Resource");
 
 				if (p_hint == PROPERTY_HINT_RESOURCE_TYPE) {
-					String open_in_new = EDITOR_GET("interface/inspector/resources_to_open_in_new_inspector");
-					for (int i = 0; i < open_in_new.get_slice_count(","); i++) {
-						String type = open_in_new.get_slicec(',', i).strip_edges();
+					const PackedStringArray open_in_new_inspector = EDITOR_GET("interface/inspector/resources_to_open_in_new_inspector");
+
+					for (const String &type : open_in_new_inspector) {
 						for (int j = 0; j < p_hint_text.get_slice_count(","); j++) {
-							String inherits = p_hint_text.get_slicec(',', j);
+							const String inherits = p_hint_text.get_slicec(',', j);
 							if (ClassDB::is_parent_class(inherits, type)) {
 								editor->set_use_sub_inspector(false);
 							}