Fix severe warning from class loader in servo

[bijoua29]

Description

To fix "SEVERE WARNING" from class loader in moveit_servo, created the class loader as a member variable instead of creating it on the stack.

This fixes the following error:

[servo_node-20] Warning: class_loader.ClassLoader: SEVERE WARNING!!! Attempting to unload library while objects created by this loader exist in the heap! You should delete your objects before attempting to unload the library or destroying the ClassLoader. The library will NOT be unloaded.

[AndyZe]

Hi Bijou, long time no see. Thanks for fixing this, it's been annoying for too long.

I don't think it needs to be a unique_ptr? But I'll still approve the PR either way.

Suggested change

	// Plugin loader
	std::unique_ptr<pluginlib::ClassLoader<online_signal_smoothing::SmoothingBaseClass>> smoother_loader_;
	// Plugin loader
	pluginlib::ClassLoader<online_signal_smoothing::SmoothingBaseClass> smoother_loader_;

[bijoua29]

Hi Bijou, long time no see. Thanks for fixing this, it's been annoying for too long.

I don't think it needs to be a unique_ptr? But I'll still approve the PR either way.

Hi @AndyZe, Sorry didn't respond earlier. Good to see you too

[AndyZe]

I pushed a small commit to satisfy the linter

[AndyZe]

Blocked pending #3567 I think

[codecov]

Codecov Report

❌ Patch coverage is 0% with 2 lines in your changes missing coverage. Please review.
✅ Project coverage is 46.19%. Comparing base (65aa94c) to head (2075ef2).
⚠️ Report is 36 commits behind head on main.

Files with missing lines	Patch %	Lines
moveit_ros/moveit_servo/src/servo.cpp	0.00%	2 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #3577      +/-   ##
==========================================
+ Coverage   46.19%   46.19%   +0.01%     
==========================================
  Files         720      720              
  Lines       62744    62742       -2     
  Branches     7595     7594       -1     
==========================================
+ Hits        28978    28980       +2     
+ Misses      33598    33596       -2     
+ Partials      168      166       -2     

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[nbbrooks]

Force merging this since Rolling CI was fixed and this is now passing.

The tutorial failure is unrelated and should be resolved by moveit/moveit2_tutorials#1071

[bijoua29]

Force merging this since Rolling CI was fixed and this is now passing.

The tutorial failure is unrelated and should be resolved by moveit/moveit2_tutorials#1071

@nbbrooks Is it possible to get this commit into the next Kilted sync. Would appreciate that.