Add support for the "Delete by Query" API

[ido50]

This commit adds support for ElasticSearch's Delete by Query API. Usage
is very similar to that of Search and Count requests:

esquery.Delete().
    Index("index_1, "index_2").
    Query(esquery.Bool()...).
    Run(
        es,
        esapi.WithAnalyzeWildcard(true),
    )

[ido50]

@oranmoshai