[ci skip] Convert tutorial jupyter notebooks to jupytext files in percent format.

docs/source/tutorials/01_tutorial_getting_started.ipynb

docs/source/tutorials/01_tutorial_getting_started.py

docs/source/tutorials/02_tutorial_basic_kernels.ipynb

docs/source/tutorials/02_tutorial_basic_kernels.py

docs/source/tutorials/03_tutorial_datahandling.ipynb

docs/source/tutorials/03_tutorial_datahandling.py

docs/source/tutorials/04_tutorial_advection_diffusion.ipynb

docs/source/tutorials/04_tutorial_advection_diffusion.py

...rials/05_tutorial_phasefield_spinodal_decomposition.ipynb

...utorials/05_tutorial_phasefield_spinodal_decomposition.py

...e/tutorials/06_tutorial_phasefield_dentritic_growth.ipynb

...urce/tutorials/06_tutorial_phasefield_dentritic_growth.py

docs/source/tutorials/demo_assignment_collection.ipynb

docs/source/tutorials/demo_assignment_collection.py

docs/source/tutorials/demo_benchmark.ipynb

docs/source/tutorials/demo_benchmark.py

docs/source/tutorials/demo_derivatives.ipynb

docs/source/tutorials/demo_derivatives.py

docs/source/tutorials/demo_plotting_and_animation.ipynb

docs/source/tutorials/demo_plotting_and_animation.py