Move executables to model [2.5/7]

[phmarti]

This PR changes the way the executable are created:

1. It's splits the PhysicalModel, which contains the setup for nonlinear simulations, state generators and visualization generators, into three independent pieces.
2. Removes the executables from the Framework, including the linear stability solver, shifting the reponsability to the Model.

This will require to modify all models. An example is done on Model-BoussinesqSphereRTC. Other models will be converted before merging.