Add configurable timeout for publishing

[samizzy]

One-line summary

Zalando ticket : 1622

Description

Add ability to specify timeout when using publishing apis and is taken from custom header X-TIMEOUT.

• This ability will allow users to fail fast in case the latency during publishing becomes too high for their use case.
• Originally if the publishing request timed out from user side (due to setting smaller client timeout) then users would assume all events failed publishing and retry the whole batch. With the addition of this custom publish timeout, they can retry only the truly failed events.

[adyach]

there is a problem with this approach: client sets 300ms timeout, connection is close by Nakadi due to timeout (300ms), but Kafka Producer continues to retry events for this request for the 29 700ms. this is a problem by itself for Nakadi, what if there are many more such requests but also it can be that the event will appear in the middle of the other published batch breaking the order.