cleaned up CreateIndex and added Tests
cleaned up Distinct and added Tests
cleaned up ExpressionScan and added tests
cleaned up GetTable and added tests
cleaned up GroupByScan and added tests
cleaned up JoinScan and added tests
cleaned up HashBuild and added tests
cleaned up HashJoinProbe and added tests
cleaned up IndexScan and added test
cleaned up InsertScan and added tests
cleaned up LayoutSingleTable and added tests
cleaned up LayoutTable and added tests
cleaned up LayoutTableLoad
cleaned up LoadFile and added tests
cleaned up MaterializingScan and added tests
cleaned up MergeJoin
cleaned up MergeTable and added tests
cleaned up MySQLTableLoad
cleaned up NoOp and adjusted namespace in units_access/taskscheduler.cpp
cleaned up ProjectionScan and added tests