separate relast preprocessor from ros2rag

src/test/resources/in/Example.relast

+Model ::= RobotArm ZoneModel ;
+
+ZoneModel ::= <Size:IntPosition> SafetyZone:Zone* ;
+
+Zone ::= Coordinate* ;
+
+RobotArm ::= Joint* EndEffector <_AttributeTestSource:int> /<_AppropriateSpeed:double>/ ; // normally this would be: <AttributeTestSource:int> ;
+
+Joint ::= <Name> <CurrentPosition:IntPosition> ;  // normally this would be: <CurrentPosition:IntPosition>
+
+EndEffector : Joint;
+
+Coordinate ::= <Position:IntPosition> ;