Integrate table streams into locally testable environment

[jracusin]

Description

Replace dynalite with dynamodb local in the sandbox environment. This will give us a much higher fidelity simulation of dynamodb for local development, which is important because synonyms use table streams, and the local sandbox environment won't behave like production unless we have table streams working.

https://martinhicks.dev/articles/arc-sandbox-table-streams

Acceptance criteria

• configure architect to launch dynamodb local
• use its endpoint for dynamodb API calls
• configure dynamodb local table streams to invoke our lambdas on changes
• discard code to work around lack of transaction support in dynalite