We should reimplement our fromjson() and fromFuzzerJson() utilities to use a third-party JSON parser. The parser at a minimum needs to support an intermediate representation of the data that we can use to build a BSONObj without inspecting the input bytes directly, or support a way to hook into parsing events such that the BSONObj can be constructed inline during parsing.

Ideally, the library would also just support parsing directly to BSON; however, this only satisfies the requirements for fromjson(). The fromFuzzerJson() utility is an extension that is aware of domain-specific object schemas like DBRef; it may be costly to parse directly to BSON and then walk the BSONObj to detect and rewrite the domain-specific objects.

Assuming we are able to use a third-party library to reimplement fromjson() and fromFuzzerJson(), delete JParser and JParserUtil.