MI-326: Add ErrorThrowingClient type utility to microservice-util-lib

[kai-nguyen-aligent]

Description of the proposed changes

• Add ErrorThrowingClient mapped type and asErrorThrowingClient cast function to @aligent/microservice-util-lib, co-located with retryMiddleware
• ErrorThrowingClient rewrites HTTP method return types to Promise<{ data: D; response: Response }>, stripping the unreachable error branch when retryMiddleware is registered with throwOnNotOk: true (the default)
• asErrorThrowingClient() is a zero-cost type narrowing — no runtime overhead
• Also export HttpResponseError and isHttpResponseError from the package barrel, enabling consumers to handle expected error status codes via try/catch

Other solutions considered

• Placing ErrorThrowingClient in consumer packages rather than microservice-util-lib — rejected because every project using retryMiddleware would need to define it independently

Notes to reviewers

• 🛈 Toggl Code: MI-326: Code Review
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