[MSA] Fix arg parsing in main

[DLu]

Description

Fix the parsing of command line arguments, so that launching MSA from a launch file does not result in an "unknown argument --ros-args" error.

It feels like there should be an easier way to do this, but this is the best I found.

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

[mergify]

Please target the main branch for development, we will backport the changes to feature/msa for you if approved and if they don't break API.

[codecov]

Codecov Report

Merging #1110 (929f5f8) into feature/msa (71d2ac5) will decrease coverage by 0.02%.
The diff coverage is n/a.

@@               Coverage Diff               @@
##           feature/msa    #1110      +/-   ##
===============================================
- Coverage        61.03%   61.02%   -0.01%     
===============================================
  Files              275      275              
  Lines            23761    23761              
===============================================
- Hits             14501    14498       -3     
- Misses            9260     9263       +3     

Impacted Files	Coverage Δ
...dl_kinematics_plugin/src/kdl_kinematics_plugin.cpp	74.82% <0.00%> (-1.11%)	⬇️

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