Pass a per-delivery key to ContainerAdapter.get, so request scopes aren't shared across retries #353

Follow-up from #352 (NestJS integration).

Problem

ContainerAdapter.get(type, context) is given { message, messageAttributes }. Nothing in that context identifies one delivery of a message. nestContainer() in @node-ts/bus-nestjs keys its per-message request scope (ContextId) by the message object, which is the only stable key it has.

That works for transports that deserialize each delivery into a new object. But InMemoryQueue retries a returned message, and re-sends the same object, without copying it. So every retry of a message shares the request-scoped instances, and the REQUEST, of its first attempt. State that a request-scoped provider builds up during a failed attempt leaks into the retry. Any other container adapter that scopes per message has the same problem.

Proposal

Have bus-core pass a per-delivery key in the container context: for example the TransportMessage being handled, which is a new object for each delivery and is already what the handling context tracks. Then nestContainer() can key its scope on that rather than on the message.

• Class handlers: invokeHandler in service-bus/bus-instance.ts calls container.get(classHandler, { message, messageAttributes }).
• Class workflows: invokerFor in workflow/registry/workflow-registry.ts calls container.get(WorkflowCtor, { message, messageAttributes }).
• Adding an optional field to the context is not a breaking change for adapters.