Add MemoryLevel, refactor type hierarchy

source/RobotAPI/libraries/armem/CMakeLists.txt

source/RobotAPI/libraries/armem/memory/CoreSegment.cpp

source/RobotAPI/libraries/armem/memory/CoreSegment.h

source/RobotAPI/libraries/armem/memory/Entity.cpp

source/RobotAPI/libraries/armem/memory/Entity.h

source/RobotAPI/libraries/armem/memory/EntityData.h

source/RobotAPI/libraries/armem/memory/EntitySnapshot.cpp

source/RobotAPI/libraries/armem/memory/EntitySnapshot.h

source/RobotAPI/libraries/armem/memory/Memory.cpp

source/RobotAPI/libraries/armem/memory/Memory.h

source/RobotAPI/libraries/armem/memory/ProviderSegment.cpp

source/RobotAPI/libraries/armem/memory/ProviderSegment.h

.../RobotAPI/libraries/armem/memory/detail/EntityStorage.cpp

...ce/RobotAPI/libraries/armem/memory/detail/EntityStorage.h

.../RobotAPI/libraries/armem/memory/detail/MemoryContainer.h

...ce/RobotAPI/libraries/armem/memory/detail/MemoryLevel.cpp

source/RobotAPI/libraries/armem/memory/detail/MemoryLevel.h