Remap joint states instead of re-publish

[rhaschke]

Re-publishing joint_states via joint_state_publisher (a python app) is highly inefficient.
IMO remapping would be the right way to go instead - as long nobody needs the published topics on the namespace
franka_state_controller / franka_gripper.

But, remapping has its drawbacks too:

• It breaks existing software relying on topics franka_state_controller/joint_states and/or franka_gripper/joint_states
• joint_states messages from arm and gripper are published both to the same topic, so we cannot easily distinguish them anymore (w/o looking at the message of course)
• The variable message format (7 vs. 2 joints) might confuse existing software, e.g. rqt_plot.

Note: This PR includes #191.

[rhaschke]

@frankaemika, what do you think of this idea? Nobody ever commented on this for 9 months.

[rickstaa]

@rhaschke, thank you for your work on improving the franka_ros package's performance! I greatly appreciate the changes made in this pull request and tried to review it to speed up the merge process.

During my review, I encountered some issues that I believe are important to address:

1. Unrecognized 'remap' Tags: When I attempted to run roslaunch franka_gazebo panda.launch, I received warnings about unrecognized 'remap' tags within the <include> tag.

2. Simulation Breakage: The simulation is broken as no messages are being published on the /joint_states topic. To temporarily address this, I moved the 'remap' command outside of the <include> tag. However, this results in two separate messages being published sequentially—one for arm joint states and another for gripper joint states.

Considering that using the joint_state_publisher is sub-optimal, perhaps we could explore a custom C++ joint publisher solution. This would involve merging arm and gripper joint states and republishing them. We might take inspiration from tools like relay.cpp in the ROS repository.

@gollth, @@FE-EnricoSartori I think @rhaschke raised a vital performance improvement opportunity. I'm interested to know what you think about this change 🤔.