Batch `DeleteMessage` to substantially increase throughput

### Describe the feature

Batch `DeleteMessage` on successful handler invocations to reduce both cost and API load, raising FIFO processing limits 5.5 times.

### Use Case

Both `ReceiveMessage` and `DeleteMessage` count towards the 300 TPS on FIFO queues.

Under load, `RecevieMessage` returns 10 messages which are then processed by individual handler invocations. Each handler calls `DeleteMessage` on completion -a total of 11 API calls per 10 messages.

The TPS count with this workflow limits message throughput to ~270 messages per second on FIFO queues and drives up the API cost unnecessarily.

### Proposed Solution

Instead of each handler calling `DeleteMessage`, it would be preferrable to batch the receipts for a single API call of 10 messages or [n] milliseconds (whichever happens first).

At maximum rate; message processing on a FIFO queue would increase from ~272 messages per second (300 / 11 * 10) to ~1500 (300 / 2 * 10) before being throttled.

### Other Information

_No response_

### Acknowledgements

- [ ] I may be able to implement this feature request
- [ ] This feature might incur a breaking change

### AWS.Messaging (or related) package versions

AWS.Messaging.*

### Targeted .NET Platform

all supported

### Operating System and version

n/a

Start by reading the AWS.Messaging handler flow around ReceiveMessage and successful handler completion, then inspect how DeleteMessage is currently invoked. Identify the SQS batching entry points and determine how a receipt batch and count-or-time trigger would be represented; done means successful receipts are deleted in batches without changing handler semantics.

Written by the indexing model from the issue text.