Add various special cases

[sebcrozet]

This adds:

• A special case for the triangle/cuboid edge-edge case in the SAT implementation.
• The contact manifold computation between a convex shape and a halfspace.
• Fix the separation computation between a cuboid and a support-map shape in the SAT implementation.
• A special case (instead of GJK) for computing closest points between two cuboids.
• A special case (instead of GJK) for computing closest points between a cuboid and a triangle.
• A special case (instead of GJK) for computing the distance between a ball and a convex shape.