Introduce and use constants for robot state memory IDs

...onents/armem/server/RobotStateMemory/RobotStateMemory.cpp

source/RobotAPI/libraries/armem_robot_state/CMakeLists.txt

source/RobotAPI/libraries/armem_robot_state/memory_ids.cpp

source/RobotAPI/libraries/armem_robot_state/memory_ids.h

...ibraries/armem_robot_state/server/description/Segment.cpp

...braries/armem_robot_state/server/localization/Segment.cpp

...aries/armem_robot_state/server/proprioception/Segment.cpp