[Service Bus] Add createBatch() to Sender

[ramya-rao-a]

The sendBatch() method on the sender in Service Bus today allows users to send multiple messages by batching them into a single message. Currently, there is no way for the user to ensure that they dont go over the allowed max size for a batch. They have to send first, and then examine the error that gets thrown in such cases.

This issue is to add a createBatch() to the sender just like we did in Event Hubs to return a "batch" to the user which they can then fill one by one until the max size is reached.

Please refer to the implementation in Event Hubs as a reference.

This work needs to happen in the feature/service-bus-track-2 branch

[Pruxis]

Also what we have noticed is that by sending multiple messages everytime a event listener is created, meaning when sending large amounts of messages in parallel or in batch your server can go out of memory.

[ramya-rao-a]

Thanks for the feedback @Pruxis!
That concern should be taken care of in #6903

[HarshaNalluru]

Draft #7527

[HarshaNalluru]

Merged #7527