Sync stack, codegen support

[XiaofeiCao]

1. Switch LRO simple sync with response's response body type from model to BinaryData(proxy method as well)

private Response<BinaryData> createWithResponse(String resourceGroupName, String accountName,
        String liveEventName, LiveEventInner parameters, Boolean autoStart, Context context)

This method is for getting activation response of LRO, for SyncAcceptedImpl.

2. LRO methods implementation change

// beginXX(with and without `Context`)
public SyncPoller<PollResult<LiveEventInner>, LiveEventInner> beginCreate(String resourceGroupName,
    String accountName, String liveEventName, LiveEventInner parameters) {
    Response<BinaryData> response = createWithResponse(resourceGroupName, accountName, liveEventName, parameters);
    // needs new `createSync` method(or `create` overload) in `PollerFactory`, or `SyncPollerFactory`
    return PollerFactory.createSync(response, this.client.getHttpPipeline(), LiveEventInner.class,
                LiveEventInner.class, this.client.getContext());
}

// normal XX(with and without `Context`)
public LiveEventInner create(String resourceGroupName, String accountName, String liveEventName,
    LiveEventInner parameters) {
    return beginCreate(resourceGroupName, accountName, liveEventName, parameters).getFinalResult();
}