Provide a batched version of EventSubscription

[ross-weir]

EventSubscription passes messages to the handler individually, this makes it difficult to perform certain operations such as handling events in a certain order or persisting event data with a database transaction, etc. Basically it just makes it hard for client code to handle events in specific ways

My example use case for batching:

https://github.com/ross-weir/Donera/blob/f28e6d5f6c3686cae4d671f73cea09e3a7a8d337/packages/indexer/src/simple-event-indexer.ts#L46-L69

Could be implemented the same as EventSubscription just pass the event batch to the function instead of individual messages

[polarker]

That's a great suggestion!