Create a feature space constructor to build from a file for python

src/feature_creation/feature_space/FeatureSpace.cpp

src/feature_creation/feature_space/FeatureSpace.hpp

src/feature_creation/node/Node.hpp

src/feature_creation/node/utils.cpp

src/feature_creation/node/utils.hpp

src/feature_creation/units/Unit.cpp

src/python/__init__.py

src/python/bindings_docstring_keyed.cpp

src/python/feature_creation/FeatureSpace.cpp