Add getJacobian tests

[marioprats]

Description

This change adds some basic tests for the RobotState getJacobian method, as a first step towards #2345. The tests cover the different types of joints (fixed, revolute, planar, prismatic) with a simple 4DOF mock robot. It also cleans up some unused code and old-style literal strings.

Checklist

• Required by CI: Code is auto formatted using clang-format
• Extend the tutorials / documentation reference
• Document API changes relevant to the user in the MIGRATION.md notes
• Create tests, which fail without this PR reference
• Include a screenshot if changing a GUI
• While waiting for someone to review your request, please help review another open pull request to support the maintainers

[codecov]

Codecov Report

Patch coverage has no change and project coverage change: +0.07% 🎉

Comparison is base (94fea79) 50.74% compared to head (772e823) 50.80%.

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #2375      +/-   ##
==========================================
+ Coverage   50.74%   50.80%   +0.07%     
==========================================
  Files         386      386              
  Lines       31970    31973       +3     
==========================================
+ Hits        16219    16241      +22     
+ Misses      15751    15732      -19     

see 5 files with indirect coverage changes

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[henningkayser]

Thank you for these test cases. Implementation looks good to me, there are still some open questions from my side. Also, how confident can we be about the angle offset 1e-04 given the fairly small delta and what is an expected tolerance?

[henningkayser]

clang-tidy has some complaints about variable naming https://github.com/ros-planning/moveit2/actions/runs/6233581824/job/16919090852?pr=2375#step:12:9507

[marioprats]

Thank you for these test cases. Implementation looks good to me, there are still some open questions from my side. Also, how confident can we be about the angle offset 1e-04 given the fairly small delta and what is an expected tolerance?

Not sure what's a good way to put bounds on the expected offset, but 1e-04 is small enough I think?
I could make it 1e-05 by also reducing the time step, which sounds right.

[sjahr]

Looks good. Just a couple of more suggestions to sprinkle more const over the code (I hope all of them work and I did not miss required mutability). But not blocking the merge