Change folder structure and installation directory of python files

CMakeLists.txt

anymal_rbprm/__init__.py

anymal_rbprm/anymal.py

anymal_rbprm/anymal_abstract.py

anymal_rbprm/anymal_contact6D.py

cmake

src/hpp/corbaserver/rbprm/anymal/__init__.py

src/hpp/corbaserver/rbprm/anymal_abstract/__init__.py

src/hpp/corbaserver/rbprm/anymal_contact6D/__init__.py