Add deepData option to vue/no-unused-properties rule

[ota-meshi]

This PR adds deepData option to vue/no-unused-properties rule.

If true, the object of the property defined in data will be searched deeply. Include "data" in groups to use this option.

e.g.

<template>
  <Foo :param="state.used">
</template>
<script>
  export default {
    data() {
      return {
        state: {
          /* ✓ GOOD */
          used: null,
          /* ✗ BAD (`state.unused` data not used) */
          unused: null
        }
      }
    }
  }
</script>