Execute all queries to the same datasource in a single request.
Uses the query index and the graph node ID index, and then a stable dependency graph sort based on node input index number in attempt to keep the original query order intact.
* introduce a new node-type ML and implement a command outlier that uses ML plugin as a source of data.
* add feature flag mlExpressions that guards the feature
Kyle Brandt
Yuri Tseretyan