Add joint from world to the floating link

[Khouloud-Hamrouni]

I added what was recommended as a solution in #230 to the different robots.

[mhubii]

thanks for fixing this @Khouloud-Hamrouni ! Will get this merged tomorrow

[mhubii]

Backporting these to humble may require updates to parsing robot description to control node, e.g.

lbr_fri_ros2_stack/lbr_bringup/launch/mock.launch.py

Line 41 in 896478d

use_sim_time=False, robot_description=robot_description

[mhubii]

/backport

[github-actions]

Backport failed for humble, because it was unable to cherry-pick the commit(s).

Please cherry-pick the changes locally and resolve any conflicts.

git fetch origin humble
git worktree add -d .worktree/backport-263-to-humble origin/humble
cd .worktree/backport-263-to-humble
git switch --create backport-263-to-humble
git cherry-pick -x 820ffb4bd8a00fc54bc1782a42f4733ea801c152 5ddb8492a092130d5faf114c94de390704d18cf2 719a24448c7a4ec26a6f19522d05fa74e27df4a3 0665e23eba31d16068fe1bcb95753fb4c8c6b840 e7e58c4972f9d579a2d40213ce06682e26cc6402 a404c9a4b552df5f5225114bade4e65888a07210 c5cf92cc108636833e49ab93efdcbc04f7e72733