Add cardinality to Stats

• Type: Story
• Status: Closed
• Priority: Minor
• Resolution: Completed
• Affects Version/s: None
• Fix Version/s: 7.2.0 GA1
• Component/s: Search Infrastructure > Framework
• Labels:
  • search-feb19
• Epic Link: Search capabilities in 7.2
• Sprint: Search | S02 Sprint 11, Search | S02 Sprint 12, Search | S02 Sprint 13, Search | S02 Sprint 14, Search | S02 Sprint 15
• Git Pull Request: https://github.com/brianchandotcom/liferay-portal/pull/67744

https://www.elastic.co/guide/en/elasticsearch/reference/6.5/search-aggregations-metrics-cardinality-aggregation.html
https://lucene.apache.org/solr/guide/7_5/the-stats-component.html