Fix introspection false mismatch: defaultValue list of objects

[SimonSapin]

In GraphQL introspection response, the defaultValue of an anrgument or input object field is represented as a JSON string that contains GraphQL syntax. If that value contains a GraphQL object value, graphql-js seems to sort its contents by input object field name whereas apollo-compiler preserves the source ordering.

This causes introspection JSON responses to be different in a way that we consider not to be meaningful: object values are semantically unordered maps. Introspection "both" mode already had code to sort object values in order to ignore these differences, but was missing the case where defaultValue is not directly an object value but a list value of object values.

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• [ ] Documentation[^2] completed
• [ ] Performance impact assessed and acceptable
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  • [ ] Manual Tests

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