Revise get/find* interface of memory base classes. Remove EntityContainerBase

source/RobotAPI/libraries/armem/CMakeLists.txt

source/RobotAPI/libraries/armem/core/base/CoreSegmentBase.h

source/RobotAPI/libraries/armem/core/base/EntityBase.h

...e/RobotAPI/libraries/armem/core/base/EntityInstanceBase.h

...e/RobotAPI/libraries/armem/core/base/EntitySnapshotBase.h

source/RobotAPI/libraries/armem/core/base/MemoryBase.h

.../RobotAPI/libraries/armem/core/base/ProviderSegmentBase.h

.../libraries/armem/core/base/detail/EntityContainerBase.cpp

...PI/libraries/armem/core/base/detail/EntityContainerBase.h

...botAPI/libraries/armem/core/base/detail/lookup_mixins.cpp

...RobotAPI/libraries/armem/core/base/detail/lookup_mixins.h