Support producing messages at specific offset

[technicalpickles]

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Is your feature request related to a problem? Please describe.

I am porting ruby-kafka consumers to karafka, and some of our consumers make use of the consumed messages offset. Specifically, we store that as metadata on logs, errors, etc

The current implementation doesn't expose the offset at all. Messages use the current size of the messages produced so far, so the first one gets 0, 1, etc.

Describe the solution you'd like

karafka.produce(message_value, key: key) should support an offset option.

Describe alternatives you've considered

It might be enough to be able to set the initial offset offset, ie start from 1337 + number of messages, isntead of just the number of messages

Additional context

https://karafka-io.slack.com/archives/C027C6M2B0U/p1736529486973089