Use multi_json for rendering

[jhollinger]

Is there an existing issue for this?

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Is your feature request related to a problem? Please describe

Config option overload.

Describe the feature you'd like to see implemented

multi_json is a popular gem (that we'd need to depend on) for automatically choosing the fastest JSON renderer your application or library has available:

MultiJson.dump({:abc => 'def'})

I've used other serializers, like grape-entity, that support it, as well as many applications. This would simplify configuration by moving it up a layer outside of our library. We could still offer an override for rare cases if we want, maybe via an extension hook.

Describe alternatives you've considered

No response

Additional context

No response