Add client directive support in GraphQLQueryRequestOptions

[jiholee17]

Adds operationFieldDirectives parameter to GraphQLQueryRequestOptions to allow passing graphql.language.Directive directives to be applied to the top-level operation field in the serialized query.

Refactors this PR #935 and requires a bit more verbose setup to build a Directive on the user side but leverages the existing Directive type instead of creating a new one, and adds it to the options field to avoid adding a parameter to GraphQLQueryRequest and for extensibility.

Open to feedback on if we want to keep the simplified Directive class from the original PR and let the user pass in that type so they don't have to construct a graphql.language.Directive like

val idempotent =
            Directive
                .newDirective()
                .name("idempotent")
                .arguments(listOf(Argument("key", StringValue.of("abc-123"))))
                .build()