Choice of MPC with integer + Foot trajectory generator after MPC in case MPC optimizes footsteps + Adapt MPC Crocoddyl with footsteps optimization to the new architecture

Switch all solo12 loading to SoloLoader + architecture to run scenarios from another script + Clean test_4 + New EulerToRotation function

Change control architecture to work in horizontal frame with reference quantities instead of relying more on estimated quantities

* Code cleaning and refactor
* Add Types, FootTrajectoryGenerator, Gait, FootstepPlanner classes
* Rename quadruped-reactive-walking qrw

Authored-by: Fanny Risbourg <frisbourg@laas.fr>