Summary

This PR adds support for using an async context (specifically from the InvokeStore package) in the Batch utility. This allows users to process batches that are isolated specifically to the current lambda invocation, isolated from any other executions.

Changes

• Added storage classes to abstract the use of InvokeStore to persist state across invocations.
• Added a storage class for the state (records, handlers, failures etc) associated with batch processing: BatchProcessingStore
• Add a storage class for SQS FIFO processing to track group IDs: SqsFifoProcessorStore
• The Batch Processor class are highly stateful with mutiple subclasses that mutate instance variables across the class hierarchy. As such I have taken a slightly different approach to incorporating the BatchProcessingStore class: if we followed the pattern of replacing all in place mutation with specific methods that guard against mutating the underlying resources, this would entail far more changes to the code across the mutliple subclasses. Instead, I have chose to use getters and setters to proxy updates to the store to ensure the the amount of changes to the code are minimised.
• Added specific concurrency tests for both stores and also the BatchProcessor and SqsFifoPartialProcessor classes that use them.

Issue number: closes #4676

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