Feature: Allow QueuePoller to be interrupted from another thread

### Describe the feature

There should be a way to cleanly stop/interrupt `QueuePoller` from another thread. It should immediately abort pending poll requests, but if the `poll` callback is executing, it should wait for that to complete before returning.

### Use Case

I would to write code like `Signal.trap("INT") { poller.stop }`, so that I may use Ctrl+C to interrupt a daemon script that is polling SQS with `QueuePoller`.

### Proposed Solution

The `QueuePoller` could have a method `stop` that can be invoked from any thread. If a call to `poll` is awaiting an SQS poll request, the request will be immediately aborted and `poll` will return normally. If `poll` is executing the callback when `stop` is invoked, then it will wait until the callback returns and then `poll` will return without making further poll requests.

### Other Information

_No response_

### Acknowledgements

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

### SDK version used

3.1.0

### Environment details (OS name and version, etc.)

macOS