We have some builders, specifically query builders, `SearchSourceBuilder`, `QuerySourceBuilder` and `SuggestBuilder`, that implement `ToXContent` and also allow to build their content as bytes by simply creating a `BytesReference` that holds their json (or yaml etc.) content (`buildAsBytes` methods). They can also print out their content through `toString`. Made sure that those common methods are in one single place and reused where needed.
Also, merged `QueryBuilder` and `BaseQueryBuilder` and made `QueryBuilder` an abstract class instead of an interface.
Closes#11063
These help a lot when refactoring, upgrading lucene, etc, and
can prevent code duplication (as you get a compile error for outdated stuff).
Closes#9832.
