chore(labs): make button and checkbox directive state optional

PiperOrigin-RevId: 900336346

Author: asyncliz

labs/gb/components/button/button.ts

@@ -178,7 +178,7 @@ class ButtonDirective extends AsyncDirective {
   private element?: HTMLElement;
   private cleanup?: AbortController;
 
-  render(state: ButtonDirectiveState) {
+  render(state: ButtonDirectiveState = {}) {
     return classMap({
       ...(state.classes || {}),
       ...buttonClasses(state),

labs/gb/components/checkbox/checkbox.ts

@@ -100,7 +100,7 @@ class CheckboxDirective extends AsyncDirective {
   private element?: HTMLElement;
   private cleanup?: AbortController;
 
-  render(state: CheckboxDirectiveState) {
+  render(state: CheckboxDirectiveState = {}) {
     return classMap({
       ...(state.classes || {}),
       ...checkboxClasses(state),