Allow input object to be required

[thetamind]

https://graphql-rules.com/rules/mutation-input-arg

Add required: true option to derive_mutation to make :input argument required.

But what effect does required: true have if input_object: false?

Maybe input_object: :required is more cohesive?

Or a config option to mark all input_objects required project wide such as when enforced by a linting rule.