use gz-physics#283 to implement joint_states/effort feedback

[andreasBihlmaier]

Fixes joint_states/effort being zero for joints with <state_interface name="effort" /> in combination with joint_state_broadcaster/JointStateBroadcaster by using the JointTransmittedWrench component introduced by gazebosim/gz-physics#283.

The joint axis is hard coded to z. I did not yet look into reading out the actual <axis> of the joint and extracting the respective force/torque component of the wrench.

[ahcorde]

Thank you for the contribution.
Two comments:

• Can you review linters?
• can you add a comment related to the hardcoded z joint ? or do you plan to continue working on this PR ?

[Nemantor]

I tried it and it works properly, couldn't find any problems

[BarisYazici]

We are currently integrating Gazebo and would like to have the efforts from simulation. How is this PR going?

[andreasBihlmaier]

I'll take a quick look this weekend whether I can get this PR cleaned up and submitted.

[andreasBihlmaier]

This should do it (further testing strongly recommended): andreasBihlmaier@59ef8f0

I'll try to either update this PR or create a new one in the next days.

[andreasBihlmaier]

I did a bit of quick testing wrsp to joint axis. The effort seems to be reported as expected.
I force pushed https://github.com/andreasBihlmaier/gz_ros2_control/tree/fix-effort-state-jazzy onto the fix-effort-state branch (GitHub does not allow to change PR source branches) and retargeted this PR to jazzy branch.

[BarisYazici]

I tested this. It works for us. Thanks a lot @andreasBihlmaier