Cache personalized responses now respect `max-age` values set at origin

Applications that leverage the cache personalization API can now specify a max-age value in the Cache-Control header returned by origins.

This value will be honored by the VIP edge, which will return a Cache-Control header with the private directive, to make sure only private caches can store the response, and the max-age directive containing the value set at origin.

Changed

Cache-Control headers for responses that leverage cache personalization now include the max-age value sent from origin, if available, instead of only specifying private.