Fix Messages Dropped By Handler

[kespinola]

Issue

Though message were being read from redis a large amount were lost when passed to the dynamic version of the handler. This would leave messages as pending, not be processed, and never acknowledged.

Changes

• Trait MessageHandler for model different variants of handling a redis message from any stream
• Implement AccountHandle, TransactionHandle, DownloadMetadataJsonHandle
• Adjust shutdown code to be able to wait for jobs and shutdown cleanly