we want to own this specialization fully so we can change the default
serializer behavior without also forcing downstream users of our code
to use the same behavior. it'll also let us do things we cannot do in
regular nlohmann::json, such as selectively enabling serialization of
enums as integral types, or using `to_json`/`from_json` overloads for
not-default-constructible types instead of serializer specializations
Change-Id: I91a1db362e37d654090f1824b1cd3ce783d32134
eldritch horrors
45017f7508