[FEATURE REQUEST] Will your add the TraceId option

[mason51]

Is your feature request related to a problem? Please describe.
I have read the asynq.Option code. There are ten options, but I can not find the trace option.

We use distributed tracing to trace every http api in our system. If I NewTask and Enqueue from a http api, I want to pass the TraceID into the distributed job.

For example:

http://frontend.xxx.com/api/buy  
        -> Enqueue TaskA  
        -> Enqueue TaskB   
                ->  call http://backend.xxx.com/api/delivery 
                        -> Enqueue TaskD
        -> Enqueue TaskC

I want to trace every procedure

[shuqingzai]

#547