Rebased the ScalarAccessor and ArrayAccessor classes onto the mtca4u::NDRegisterAccessorBridge class.
Known problems present: code compiles but tests do not run

Forward declaration is taken from DeviceAccess header file, which solves problems if classes are moved to another namespace.

allow specifying the array length for direct connections between device and control system (as the type is already defined in this case)

Introduced the DeviceModule class which provides an interface to obtain VariableNetworkNodes for device registers