Compression and JustSaying 8.0 Changes

[slang25]

There is still more to go, but I'm pushing this now to get some feedback.

This PR makes the following changes:

• Adds message compression
• Introduces a "Message Body Serializer/Deserializer" to keep the message format separate
• Adds SNS raw delivery support
• Fixes missing message attributes for subscribing messages that were directly sent to an SQS queue (i.e. without SNS wrapper)
• Removes subscription reliance on Subject
• Allows for publishing override for Subject
• Removes serialization registry, serializers are flowed through the subscription.
• Added LocalSqsSnsMessaging to make integration testing instantaneous.
• Made more types internal

Outstanding actions:

• Integration tests for subject override
• Add subject override to all publishers
• Integration tests for more scenarios
• Revert samples app
• Add missing XML doc comments
• Add documentation