fix(click-outside): correctly remove event handlers in Shadow DOM

Use beforeUnmount instead of unmounted to remove event handlers in
click-outside directive, since it's not possible to get element's
shadowRoot when the element is already unmounted.

fixes vuetifyjs#19616

packages/vuetify/src/directives/click-outside/index.ts

@@ -102,7 +102,7 @@ export const ClickOutside = {
     }
   },
 
-  unmounted (el: HTMLElement, binding: ClickOutsideDirectiveBinding) {
+  beforeUnmount (el: HTMLElement, binding: ClickOutsideDirectiveBinding) {
     if (!el._clickOutside) return
 
     handleShadow(el, (app: HTMLElement) => {