Use cache when converting dataflow to SQL #1637
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While building the dataflow plan, we sometimes call
node_data_set_resolver.get_output_data_set(node). This resolves the data set for a given node, and uses a cache if the exact same node has already been resolved. Later, we again resolve the same nodes when we go through the dataflow to SQL DAG. This DAG does not make use of the cache.This PR updates the dataflow to SQL DAG to make use of the cache so that we don't resolve the same exact node twice.
This results in quite a lot of snapshot changes, all of which are just changes to the subquery aliases. This is because we were generating a bunch of aliases when building the dataflow plan that didn't get used, resulting in higher increments for the aliases that actually got used.