turek-hron-fsi3: Add FEniCS as solid participant

[BenjaminRodenberg]

I'm adding this issue as a summary of the current state and collection of useful resources, because it just took me a bit of time to reconstruct what has happened to this case during the last few years.

1. @richahert computed the FSI3 case with FEniCS in his thesis, section 5.2. Important: He used a linear solver. The case was contributed via FEniCS OpenFOAM perp-flap and cyl-flap #38.
2. In Restructure tutorials #125 we decided to remove FEniCS as a solid participant from the case. Main reason: because the linear solver does not yield sufficiently accurate results.

Adding FEniCS as a solid participant would be helpful for cross-comparison to other solvers (this already helped us to debug the perpendicular flap case, see #250). FEniCS also gives very direct control over the time-stepping scheme being used, which might give us additional understanding for the case (e.g. in https://precice.discourse.group/t/turek-hron-fsi-with-openfoam-and-calculix/1001/14).

I marked this issue as a student issue, because it might be a nice thesis topic.