Improve Steering Controller Tests

Yes, you're right, there are a lot of things open to test -- but right now I just wanted to provide a quick fix for the Ackermann odometry, only rudimentary tested. Maybe we should open a new issue, tagged "help wanted" for proper testing of the steering lib -- starting with tests for the integrator functions, etc. But maybe first we should check for a redesign cf. #692

ok, I'll create a new issue then.

BTW, I just added this file 'test_steering_odometry.cpp', with some hard-coded tests. Is that the way to go, or do we want to have a more advanced testing style?

Should the expectations of the FW kinematics be true for all the different kinematic configurations? Then we could change this to a parameterized test as we have with JTC
https://github.com/ros-controls/ros2_controllers/blob/1d0d7531ef8d24ea52e761a872b8bf277652dd33/joint_trajectory_controller/test/test_trajectory_controller_utils.hpp#L695-L710

https://github.com/ros-controls/ros2_controllers/blob/1d0d7531ef8d24ea52e761a872b8bf277652dd33/joint_trajectory_controller/test/test_trajectory_controller.cpp#L1840-L1849

Originally posted by @christophfroehlich in https://github.com/ros-controls/ros2_controllers/issues/921#issuecomment-1851853293