Add Robot ground contact

[JackyBloxx]

Add a possability to contact if the robot stands on the ground or is hold in the air.

[alexschmander]

Starting from #2178, the SupportSide, which is needed by the ground_provider, is simply faked as always being SupportSide::Left. This should either be fixed by rewriting the ground_contact_detector or computing the camera_matrix without using the forward kinematic through the ground (see 3D SLAM).