This PR introduces new api to dash table TraversingBuckets which traveses table by physical buckets
when creating a snapshot we now call this api. The snapshot correctness stays and there are less calls to Serialize bucket callback as it is called only once per bucket and not on every slot
This PR introduces new api to dash table TraversingBuckets which traveses table by physical buckets when creating a snapshot we now call this api. The snapshot correctness stays and there are less calls to Serialize bucket callback as it is called only once per bucket and not on every slot