Previously, ForEachNodeCached would batch fetch node _feature_ data but
would still fetch the channel set of each node in a node-by-node fashion
which is not ideal. So this commit updates this method to make use of
the new sqldb.ExecuteCollectAndBatchWithSharedDataQuery helper. It lets
us batch load channel data for a range of node IDs.
This _greatly_ improves the performance of the method.
Elle Mouton
dc6f9256bc