[wpgen] Externalize RF computation

include/sot/talos_balance/dummy-walking-pattern-generator.hh

python/sot_talos_balance/create_entities_utils.py

...n/sot_talos_balance/test/appli_dcmZmpControl_estimator.py

src/dummy-walking-pattern-generator.cpp

unittest/python/test_dummy_wpgen.py