Add additional function to setup that allows to type StateNodeConfigs outside of createMachine

[WIStudent]

I have a rather large state machine (the config is over 1000 lines long) with multiple parallel and parent states. In xstate 4, it was possible to put the definition of the parallel and parent states in separate variables, put everything together in createMachine, and still have strong type safety using typegen. To have strong type safety in xstate 5, the entire configuration must be to be declared in the createMachine function returned by the setup function. For larger machines, this becomes difficult to navigate. That's why I would like to suggest an additional function createStateNodeConfig, which is returned by the setup function. The implementation of the setup function could look like this:

export function setup<
    // unchanged, omitted for better readability
>(setupArgs): { // unchanged, replaced in this example with setupArgs for better readability
    // createMachine omitted for readability
    createStateNodeConfig: <
        TStateNodeConfig extends StateNodeConfig<
            TContext,
            TEvent,
            ToProvidedActor<TChildrenMap, TActors>,
            ToParameterizedObject<TActions>,
            ToParameterizedObject<TGuards>,
            TDelay,
            TTag,
            TOutput,
            TEmitted,
            TMeta
        >
    >(
        config: TStateNodeConfig
    ) => TStateNodeConfig;
} {
    return {
        // createMachine omitted for readability
        createStateNodeConfig: (stateNodeConfig) => stateNodeConfig
    };
}

This would then allow to define the states like this:

const {createMachine, createStateNodeConfig} = setup({
  types: {
    events: {} as  {type: "EVENT_A"} | {type: "EVENT_B"}
  },
  actions: {
    foo: () => {}
  },
  actors: {
    bar: fromPromise(async () => {})
  }
});

const parallel1 = createStateNodeConfig({
  initial: "p1state1",
  states: {
    p1state1: {
      on: {
        EVENT_A: {
          target: 'p1state2'
        }
      }
    },
    p1state2: {
      type: "final"
    }
  }
})

const child = createStateNodeConfig({
  initial: 'child1',
  states: {
    child1: {
      on: {
        EVENT_B: {
          target: "child2"
        }
      }
    },
    child2: {
      type: "final"
    }
  }
})

const parallel2 = createStateNodeConfig({
  initial: "p2state1",
  states: {
    p2state1: {
      on: {
        EVENT_A: {
          target: 'p1state2'
        }
      }
    },
    child: {
      ...child,
      onDone: {
        target: 'p2state2'
      }
    },
    p2state2: {
      type: "final"
    }
  }
})

createMachine({
  type: "parallel",
  states: {
    parallel1,
    parallel2
  }
});

Full example in typescript playground