Depends on D4580
This is the base code for the performance tests for the Blob service.
I used `tokio` here as I was having problems with `thread::spawn` `thread::join` working with the `async` closures - @varun have you done anything like this? I'm not saying that tokio's bad here - there's some additional boilerplate but not too much - acceptable I'd say.
The idea here is to simultaneously run service calls (they're async) in multiple threads.