EachMessage logic is buggy

[ThisIsMissEm]

It's possible within one consumer group to overwrite the offsets committed by one consumer from another due to the logic in eachMessage.

Rather than deciding in eachMessage's callbacks whether to commit, it should be a function on "did all callbacks execute successfully?" Otherwise different consumers may commit different offsets to the same topic and consumer group.

This would also simplify out code here, since we wouldn't need any promise wrapping, we can just Promise.allSettled on registered handlers, and filter to detect rejections