IssueTracker

I'd like to request a way to specify, as part of a work request, a maximum number of times a worker will be retried before considering the worker to have failed.

Oftentimes, we have jobs that we'd like to retry - for example, if network cuts out during a background upload - but we don't want to retry them indefinitely.  It would be very useful to specify this as part of the work request, especially for jobs for which we wouldn't otherwise manually track state:

```
class MyWorker extends Worker {
  @Override
  WorkerResult doWork() {
    try {
      doSomeNetworkThing();
      return WorkerResult.SUCCESS;
    } catch (IOException e) {
      // Oh no, the network is spotty.  Retry, unless this is the Nth attempt, in which case
      // just fail
      if (/**/) {  //
        return WorkerResult.RETRY;
      } else {
        return WorkerResult.FAILURE;
      }
    }
  }
}
```

It would be nice if, instead, we could do this declaratively:

```
new OneTimeWorkRequest.Builder(MyWorker.class)
    .setBackoffPolicy(BackoffPolicy.exponential().withMaxRetries(10)) // let's just pretend this API exists
    .build();
```

The above API would specify a policy such that, if the `MyWorker#doWork()` returns `WorkerResult.RETRY` 10 times, the scheduler will consider that to be equivalent to `WorkerResult.FAILURE`.