Support "multi_terms" Aggregation

[sanvir10]

Elasticsearch add new type of Aggregation in version 7.12: https://www.elastic.co/guide/en/elasticsearch//reference/master/search-aggregations-bucket-multi-terms-aggregation.html

Regards.

[sudo-suhas]

@sanvir10 would you be interested in creating a PR for the same?

[miralaur]

something like this: class MultiTerms extends Aggregation { constructor(name) { super(name, 'multi_terms'); this._aggsDef.terms = []; }

terms(terms) { this._aggsDef.terms = [...terms]; return this; } }