feat: workqueue finalization

[yarolegovich]

• Added CallContext field to workqueue.Message struct
• Added workqueue.NewInMemory
• Implemented limiter.ConcurrencyConfig handling in workqueues
• Implemented a default CallContext codec so that service params and auth information can be restored for execution
• Added BeforeExecutionCallback and AfterExecutionCallback for workqueue.PullQueueConfig as extension points for implementing custom context injection and execution result handling (complete or return a message)
• Push queues have total control over invoking execution so no need for adding callbacks there. Added a workqueue.WriterFunc for creating writer decorators.
• Fixed testutil.Logger to use AttachToContext instead of slog.SetDefault which was problematic for parallel tests

[gemini-code-assist]

Code Review

This pull request introduces cross-process context propagation for distributed task execution by adding a ContextCodec interface and implementing it for call contexts (user identity, service parameters, and tenant data). It also enhances the work queue infrastructure by implementing concurrency limiting via a new semaphore utility across in-memory, pull, and push queue variants, and adds execution callbacks to the pull queue. The review feedback highlights several critical issues: potential nil pointer dereferences in the work queues if used before handler registration, unreachable error handling logic in the pull queue, and data integrity concerns regarding shallow copies of service parameters and fragile type assertions during context decoding.

[gemini-code-assist]

If handleErr is ErrMalformedPayload, calling msg.Return contradicts the definition of ErrMalformedPayload as a non-retryable error. Returning it to the queue will cause it to be redelivered and fail again. Such errors should result in the message being completed (and optionally moved to a Dead Letter Queue).