[ServiceWorker] Introduce `Service-Worker-Max-Age` header (#721)

@ehsan, please correct me if this didn't match what we discussed.

Since service workers use byte-for-byte comparison rather than HTTP cache semantics, there's a risk that when using a service worker library, it becomes harder to update, since you need to change the library code.

So it would be good that in addition to the byte-for-byte comparison, there's also a header that indicates when the browser should start ignoring the service worker being byte-for-byte identical.

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Reply to this email directly or view it on GitHub:
https://github.com/slightlyoff/ServiceWorker/issues/721