Add training tasks to Ruta Tutorial

[DavidHuebner]

Is your feature request related to a problem? Please describe.
We received positive feedback from learners that went through the IRuta tutorials. The main feedback that we received is that additional training tasks (where learners need to implement their own solution) would be helpful.

Describe the solution you'd like
We should add some training tasks to the tutorial. As a minimal goal, we should have one training task for Exercises 1-7 for chapter 1.