feat(useOverlay)!: handle programmatic modals and slideovers (#3279)

Co-authored-by: Benjamin Canac <canacb1@gmail.com>

playground/app/components/ModalExample.vue

@@ -1,15 +1,15 @@
 <script setup lang="ts">
-const modal = useModal()
-
 defineProps<{
   count: number
 }>()
+
+const emit = defineEmits(['close'])
 </script>
 
 <template>
   <UModal :title="`This modal was opened programmatically ${count} times`">
     <template #footer>
-      <UButton color="neutral" label="Close" @click="modal.close()" />
+      <UButton color="neutral" label="Close" @click="emit('close')" />
     </template>
   </UModal>
 </template>