Geodesic Distance Computation Improvements

The goal of the project is to add the "Virtual Source Propagation" (Trettner, Bommes, Kobbelt 2021) algorithm to CGAL. This algorithm finds approximate geodesic paths and distance by propagating virtual geodesic sources along the mesh. By the time of the midterm evaluation, we intend to have a working algorithm, some tests and first optimisations. During the second coding phase, we want to further optimise the code and add CPU parallelisation. Afterwards, all the geodesic paths computation methods will be compared in term of accuracy, speed and how they scale with the mesh size and geodesic length so that CGAL users can choose the algorithm that is the best fit for their problem.