Cleanup and add Implementation pointer to Animation classes

[luca-della-vedova]

Note! This PR introduces a dependency on ign-utils1 for the implementation pointer.

There was a static map hack added in ign-common3 to add a member variable to the Animation class that didn't have an implementation pointer.
This PR removes the hack, as well as adding an implementation pointer to all the classes in the file and doing some scattered cleanups mainly:

• Templating the CreateKeyFrame function. Since both PoseAnimation and NumericAnimation had the same code with the only difference being the type I thought it might be good to remove the duplicated code and create an Animation templated function.
• Change from raw to shared pointers for splines, just to be able to remove the custom destructor and make sure there is no issues in case of objects being copied and deleted. Tthere was no copy operator in either PoseAnimation or Animation and they all had raw pointer member variables that were deleted on destruction. If there happened to be a copy created and destructed, the memory would be freed and the original wouldn't be able to access it anymore.

Also I removed a few const from functions that were changing the state like BuildInterpolationSplines(). They were able to "get away with it" since there is a lot of mutable member variables but I can revert that if it's not a great idea.

Finally, I'm tempted to remove all the unit tests for copy / copy assignment / move operators for TrajectoryInfo since they are now just the default ones and they should be tested by the ImplPtr tests.

[codecov]

Codecov Report

Merging #160 (cf18eb0) into main (1123a41) will decrease coverage by 0.03%.
The diff coverage is 94.73%.

@@            Coverage Diff             @@
##             main     #160      +/-   ##
==========================================
- Coverage   75.74%   75.71%   -0.04%     
==========================================
  Files          73       73              
  Lines       10474    10428      -46     
==========================================
- Hits         7934     7896      -38     
+ Misses       2540     2532       -8     

Impacted Files	Coverage Δ
graphics/src/Animation.cc	94.02% <94.73%> (+2.12%)	⬆️

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[chapulina]

This PR introduces a dependency on ign-utils1

I ticketed #161 to keep track of that.

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CI is all green right now because it's skipping the graphics component:

   -- 	Cannot build component [graphics] - Missing: ignition-utils1

[chapulina]

@osrf-jenkins run tests again, thanks!

[mjcarroll]

The Focal action is a performance test, so I think we're okay there.

The Windows failures are AV related, which I also believe are expected

The MacOS failure is a bit suspicious, reinterpet_pointer_cast is added in 17, which should be available on MacOS. @scpeters do you have any insight here?

[mjcarroll]

@osrf-jenkins retest this please