Investigate automatic input and output schema detection in `attach-query` and `attach-mutation`

[acron0]

It's theoretically possible to discern the schemas from the fdef (if one exists) rather than have the user supply schema.

For example, instead of (attach-query ::input ::output handler) you could just do (attach-query handler) and the function would find an fdef associated with handler, detect the :args and :ret (thanks @devurandom) and use these in place of input and output specs.

This is just sugar, really, but might help with onboarding

[devurandom]

There is s/get-spec to retrieve the spec of a fully qualified symbol. It should contain :args and :ret keys.

[workshub]

@tolgraven started working on this issue via WorksHub.

[workshub]

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[workshub]

A user started working on this issue via WorksHub.