[T] update and polish some CT and RT jupyter notebooks
Lifting 3 jupyter notebooks to our latest standard regarding post-processing, i.e. replacing vtuIO usage with ogstools and using its Project interface for running simulations instead of calling OGS via subprocess. Also adding some assertions and improving the plotting.
- DiffusionSorptionDecay.py
- MultiLayerDiffusion.py
- RadionuclidesMigration.py