Implement application case quality checks

[uekerman]

We will analyze the quality of the existing application cases in the preCICE ecosystem. As explained above, these encompass the preCICE tutorials (currently 22 cases) and other cases hosted in third-party locations. Every tutorial case should fulfill the application case standard, but not every application case should become a tutorial. Likely, we will reduce the tutorial cases to a more reasonable set and make the sorted-out cases “normal” application cases. This means that these cases will be moved to another location (another GitHub repository and/or any data archive). Reducing the tutorial cases will make them easier to maintain in the long run. This is, in particular, important, as the tutorial cases always need to be updated to newest preCICE, adapter, and solver versions.