Fire Multiple Publishing

- [ ] has-reproduction
- [X] feature
- [ ] blocking
- [ ] good first issue

Hi,

Is it possible to fire multiple events at the same time by ```pubsub.publish```

For example,
```
ctx.pubsub.publish(["event_1","event_2","event_3"], { TaskAdded: updatedTask });
```
It likes that ```pubsub.asyncIterator(["event_1","event_2"])``` which accepts array as params.

Start by reading the pubsub.publish API and comparing its current argument handling with pubsub.asyncIterator, which already accepts an array. Determine the intended behavior for publishing to event_1, event_2, and event_3 from one call, then confirm that the documented example works without changing existing single-event behavior.

Written by the indexing model from the issue text.