fix: ensure attached objects update during motion execution

[MarcoMagriDev]

Description

• Check that attached objects in the monitored robot match those in the planned trajectory.
• If an object disappears from the monitored robot, remove it from the trajectory way-point robot_state. (avoid false positives, stop trajectories due to collisions between environment and objects that are not attached to the robot anymore)
• If an object is attached to the monitored robot but missing in the trajectory, add it to enable meaningful collision checking. (avoids disruptive condition in which even if the object has been added to the robot as attached collision object it is not considered for online collision checking)

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Implications

This could impact a few different situations:

• Imagine you’re catching an object during motion, and an external node tells the planning scene to add the new attached collision object. Even though MoveIt knows about the new attached object, the collision check still only considers the attached objects that were there at the planning stage, so it misses the new one. This could lead to a situation where a collision is missed because the newly attached object isn’t part of the check.
• Similarly, dropping an object during motion may result in preempting a valid path due to a non existsent collision.

[codecov-commenter]

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Codecov Report

Attention: Patch coverage is 0% with 42 lines in your changes missing coverage. Please review.

Project coverage is 45.57%. Comparing base (7db0bd4) to head (db6d93f).

Files with missing lines	Patch %	Lines
...ros/planning/plan_execution/src/plan_execution.cpp	0.00%	37 Missing ⚠️
moveit_core/robot_state/src/robot_state.cpp	0.00%	5 Missing ⚠️

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Additional details and impacted files

@@            Coverage Diff             @@
##             main    #3327      +/-   ##
==========================================
- Coverage   45.97%   45.57%   -0.39%     
==========================================
  Files         716      716              
  Lines       62477    62491      +14     
  Branches     7564     7572       +8     
==========================================
- Hits        28715    28475     -240     
- Misses      33594    33850     +256     
+ Partials      168      166       -2     

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[sea-bass]

Mostly looks good to me, with some minor comments!

Also tagged a few other maintainers for a second look.