message: refactor: rename C to contextValue
diff: @@ -220,14 +220,14 @@ function useHandler(config: {
  };
  }, {});
  - const C = isContextFn(sofa.context)
  + const contextValue = isContextFn(sofa.context)
  ? await sofa.context({ req, res })
  : sofa.context;
  const result = await sofa.execute({
  schema: sofa.schema,
  source: print(operation),
  - contextValue: C,
  + contextValue,
  variableValues,
  operationName: info.operation.name && info.operation.name.value,
  });
  