Remove internal Span container

[sbaldu]

No description provided.

[codecov-commenter]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 87.01%. Comparing base (1f82757) to head (684d96a).
⚠️ Report is 15 commits behind head on main.

Additional details and impacted files

@@            Coverage Diff             @@
##             main     #294      +/-   ##
==========================================
+ Coverage   86.81%   87.01%   +0.20%     
==========================================
  Files          71       70       -1     
  Lines        2974     3020      +46     
  Branches       89       89              
==========================================
+ Hits         2582     2628      +46     
  Misses        392      392              

Flag	Coverage Δ
unittests	87.01% <100.00%> (+0.20%)	⬆️

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Files with missing lines	Coverage Δ
...lude/CLUEstering/core/detail/ClusteringKernels.hpp	100.00% <100.00%> (ø)
...Estering/data_structures/detail/AssociationMap.hpp	89.37% <ø> (ø)
...CLUEstering/data_structures/internal/TilesView.hpp	100.00% <100.00%> (ø)

... and 6 files with indirect coverage changes

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