Rename "Convert to Mesh2D" to "Convert to MeshInstance2D" in the editor

These actions create MeshInstance2D nodes, not Mesh2D resources.

editor/plugins/sprite_editor_plugin.cpp

@@ -335,7 +335,7 @@ void SpriteEditor::_convert_to_mesh_2d_node() {
 	mesh_instance->set_mesh(mesh);
 
 	UndoRedo *ur = EditorNode::get_singleton()->get_undo_redo();
-	ur->create_action(TTR("Convert to Mesh2D"));
+	ur->create_action(TTR("Convert to MeshInstance2D"));
 	ur->add_do_method(EditorNode::get_singleton()->get_scene_tree_dock(), "replace_node", node, mesh_instance, true, false);
 	ur->add_do_reference(mesh_instance);
 	ur->add_undo_method(EditorNode::get_singleton()->get_scene_tree_dock(), "replace_node", mesh_instance, node, false, false);
@@ -511,7 +511,7 @@ SpriteEditor::SpriteEditor() {
 	options->set_text(TTR("Sprite"));
 	options->set_icon(EditorNode::get_singleton()->get_gui_base()->get_icon("Sprite", "EditorIcons"));
 
-	options->get_popup()->add_item(TTR("Convert to Mesh2D"), MENU_OPTION_CONVERT_TO_MESH_2D);
+	options->get_popup()->add_item(TTR("Convert to MeshInstance2D"), MENU_OPTION_CONVERT_TO_MESH_2D);
 	options->get_popup()->add_item(TTR("Convert to Polygon2D"), MENU_OPTION_CONVERT_TO_POLYGON_2D);
 	options->get_popup()->add_item(TTR("Create CollisionPolygon2D Sibling"), MENU_OPTION_CREATE_COLLISION_POLY_2D);
 	options->get_popup()->add_item(TTR("Create LightOccluder2D Sibling"), MENU_OPTION_CREATE_LIGHT_OCCLUDER_2D);