Support all groups in srv_kinematics_plugin

[stephanie-eng]

Description

Srv_kinetmatics_plugin claims to support any group, including non-chains.

However, it doesn't implement supportsGroup. This will default to not supporting non-chains, which is contrary to the comment above.

This MR implements supportsGroup for srv_kinetmatics_plugin such that it supports pretty much anything.

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 is 0% with 5 lines in your changes missing coverage. Please review.
✅ Project coverage is 46.26%. Comparing base (c154f94) to head (127c0de).

Files with missing lines	Patch %	Lines
...rv_kinematics_plugin/src/srv_kinematics_plugin.cpp	0.00%	5 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #3702      +/-   ##
==========================================
+ Coverage   46.22%   46.26%   +0.05%     
==========================================
  Files         726      726              
  Lines       59503    59501       -2     
  Branches     7623     7626       +3     
==========================================
+ Hits        27499    27523      +24     
+ Misses      31836    31812      -24     
+ Partials      168      166       -2     

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