Calculates penetration vector for EPA algorithm

Adds `penetration_vector` to the `epa_result` struct to represent the direction and magnitude of penetration.

This allows for more accurate collision response calculations and simplifies access to penetration information.

Updates both the early-exit and iterative EPA calculations within `epa_algorithm.hpp` to compute and store the penetration vector, factoring in the relative origin of the colliding meshes.

include/omath/collision/mesh_collider.hpp

@@ -31,6 +31,11 @@ namespace omath::collision
             return m_mesh.vertex_to_world_space(find_furthest_vertex(direction));
         }
 
+        [[nodiscard]]
+        const VertexType& get_origin() const
+        {
+            return m_mesh.get_origin();
+        }
     private:
         MeshType m_mesh;
     };