Implement Push Consumers

[mtmk]

Discussed in #685

^{Originally posted by yang-xiaodong December 2, 2024}
I see that push-based consumers are not currently supported, and I was wondering if pull-based consumers support DeliverGroup for effects similar to Kafka Consumer Groups (A event sent to multiple groups, with load balancing of consumers within groups).

We need to implement push consumers. API wise i suggest a new method similar to ordered consumers:

ValueTask<INatsJSPushConsumer> CreatePushConsumerAsync(...);