Added score support to `has_child` and `has_parent` queries. Both queries support a score_type option. The has_child support the same options as the top_children query and the none option which is the default and yields the current behaviour. The has_parent query support the score type options: score and none. The latter is the default and yields the current behaviour.

If the score_type is set to a value other than none then the has_parent query map the matched parent score into the related children documents. The has_child query then map the matched children documents into the related parent document. The score_type on both queries defines how the children documents scores are mapped in the parent documents. Both queries are executed in two phases. First phase collects the parent uid values of matching documents with an aggregated score per parent uid value. In the second phase either child or parent typed documents are emitted as hit that have the same parent uid value as found during the first phase. The score computed in the first phase will be used as score.

Closes #2502

Added score support to `has_child` and `has_parent` queries. Both queries support a score_type option. The has_child support the same options as the top_children query and the none option which is the default and yields the current behaviour. The has_parent query support the score type options: score and none. The latter is the default and yields the current behaviour.

If the score_type is set to a value other than none then the has_parent query map the matched parent score into the related children documents. The has_child query then map the matched children documents into the related parent document. The score_type on both queries defines how the children documents scores are mapped in the parent documents. Both queries are executed in two phases. First phase collects the parent uid values of matching documents with an aggregated score per parent uid value. In the second phase either child or parent typed documents are emitted as hit that have the same parent uid value as found during the first phase. The score computed in the first phase will be used as score.

Closes elastic#2502