feat(Modal): add fullscreen prop (#523)

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

docs/components/content/examples/ModalExampleFullscreen.vue

@@ -0,0 +1,33 @@
+<script setup>
+const isOpen = ref(false)
+</script>
+
+<template>
+  <div>
+    <UButton label="Open" @click="isOpen = true" />
+
+    <UModal v-model="isOpen" fullscreen>
+      <UCard
+        :ui="{
+          base: 'h-full flex flex-col',
+          rounded: '',
+          divide: 'divide-y divide-gray-100 dark:divide-gray-800',
+          body: {
+            base: 'grow'
+          }
+        }"
+      >
+        <template #header>
+          <div class="flex items-center justify-between">
+            <h3 class="text-base font-semibold leading-6 text-gray-900 dark:text-white">
+              Modal
+            </h3>
+            <UButton color="gray" variant="ghost" icon="i-heroicons-x-mark-20-solid" class="-my-1" @click="isOpen = false" />
+          </div>
+        </template>
+
+        <Placeholder class="h-full" />
+      </UCard>
+    </UModal>
+  </div>
+</template>