Make JSON support Optional via Feature Flag

[tustvold]

Is your feature request related to a problem or challenge? Please describe what you are trying to do.

Currently arrow-rs always compiles the JSON related logic, not only does this always bring some non-trivial dependencies, but is itself a non-trivial amount of code

Describe the solution you'd like

I would like an optional json feature, much like there are already feature flags for ipc and csv.

Describe alternatives you've considered

We could not do this

Additional context

#2296