DRILL-4132 Ability to submit simple type of physical plan directly to EndPoint DrillBit for execution. There are multiple changes to achieve this: 1. During physical planning split single plan into multiple based on the number of minor fragments of the Leaf Major fragment. a. Removing exchange operators during planning b. Producing just root fragments (that will be also leaf fragments) 2. Each fragment can be executed against Drillbit it is assigned to, so to keep locality Design document can be found in the JIRA: DRILL-4132