test(useOverlay): add composable tests (#4482)

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

test/mocks/MockModal.vue

@@ -0,0 +1,22 @@
+<template>
+  <div class="mock-modal">
+    <h2>{{ title }}</h2>
+    <p>{{ description }}</p>
+    <button
+      @click="$emit('close', 'test-result')"
+    >
+      Close
+    </button>
+  </div>
+</template>
+
+<script setup lang="ts">
+const { title = 'Test Modal', description = 'Test Description' } = defineProps<{
+  title?: string
+  description?: string
+}>()
+
+defineEmits<{
+  close: [value: string]
+}>()
+</script>