Mesh connectivity functions are not tested

[IshaanDesai]

The following API functions currently do not have tests:

• set_mesh_edge (and correspondingly also the new incoming function set_mesh_edges)
• set_mesh_triangle (and correspondingly also the new incoming function set_mesh_triangles)
• set_mesh_quad (and correspondingly also the new incoming function set_mesh_quads)
• is_mesh_connectivity_required (new replacement is called requires_mesh_connectivity_for)