Cleanup msg includes: Use C++ instead of C header (backport #1844)

[rhaschke]

Replacing #1847

[mergify]

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

[rhaschke]

I really don't understand why GHA fails with including a moveit_msgs header file here.
Running industrial_ci locally works as expected.

[codecov]

Codecov Report

Base: 50.94% // Head: 50.94% // No change to project coverage 👍

Coverage data is based on head (8b561d0) compared to base (fa640f8).
Patch has no changes to coverable lines.

Additional details and impacted files

@@           Coverage Diff           @@
##           humble    #1849   +/-   ##
=======================================
  Coverage   50.94%   50.94%           
=======================================
  Files         381      381           
  Lines       31891    31891           
=======================================
  Hits        16244    16244           
  Misses      15647    15647           

Impacted Files	Coverage Δ
.../distance_field/src/propagation_distance_field.cpp	93.84% <ø> (ø)
moveit_ros/moveit_servo/src/servo_calcs.cpp	66.57% <ø> (ø)
...dl_kinematics_plugin/src/kdl_kinematics_plugin.cpp	75.36% <0.00%> (-1.07%)	⬇️
moveit_core/robot_state/src/robot_state.cpp	47.83% <0.00%> (-0.07%)	⬇️
...nning_scene_monitor/src/planning_scene_monitor.cpp	45.65% <0.00%> (+0.44%)	⬆️

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