Props destructure default value

[dbzx10299]

This is just an idea, and I know why it doesn‘t work, but it would be a cool feature to support.

<script setup lang="ts">
const { a, b = a } = defineProps<{
  a: string;
  b?: string;
}>()
</script>

[skirtles-code]

I think this is the same idea as #12386.