MOLE.jl: Add a channel flow past a cylinder example

[valeriabarra]

MOLE has a channel flow around a cylinder example, currently available in MATLAB/Octave and C++.

We want to showcase the same example in the Julia implementation.

[github-actions]

This issue has had no activity for 14 days. It will be marked stale in 14 days if there is no further activity.

[github-actions]

Thanks for the discussion and work here. This issue has had no activity for 28 days, so it is now marked stale. If there is no further activity, it will be closed in 42 days.