Support querying with SQL

[mkrauser]

It would be nice, if elastica would support querying the _sql of (Elastic|Open)Search. ppl might be another option, but for afaik OpenSearch only.

See:

• https://www.elastic.co/de/what-is/elasticsearch-sql
• https://opensearch.org/docs/latest/search-plugins/sql/index/
• https://opensearch.org/docs/latest/search-plugins/sql/ppl/index/

[ruflin]

++ on supporting SQL in Elastica. But there are currently no plans for Elastica to support OpenSearch.