Add diagnostic function to visualize shapes superimposed on datasets

[stefmolin]

• Add diagnostic function to visualize shapes superimposed on datasets
• Update shape creation tutorial to show example of using the shape diagnostic function
• Update all shape docs to use the diagnostic function
• Add tests for LineCollection and Dataset plot() methods

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 99.55%. Comparing base (b819859) to head (eea8f3b).
⚠️ Report is 4 commits behind head on main.

Additional details and impacted files

@@            Coverage Diff             @@
##             main     #331      +/-   ##
==========================================
+ Coverage   98.38%   99.55%   +1.16%     
==========================================
  Files          84       86       +2     
  Lines        2167     2232      +65     
  Branches      130      136       +6     
==========================================
+ Hits         2132     2222      +90     
+ Misses         32        8      -24     
+ Partials        3        2       -1     

Files with missing lines	Coverage Δ
src/data_morph/data/dataset.py	100.00% <100.00%> (+26.82%)	⬆️
src/data_morph/plotting/diagnostics.py	100.00% <100.00%> (ø)
src/data_morph/shapes/circles/bullseye.py	100.00% <ø> (ø)
src/data_morph/shapes/circles/circle.py	100.00% <ø> (ø)
src/data_morph/shapes/circles/rings.py	100.00% <ø> (ø)
src/data_morph/shapes/lines/diamond.py	100.00% <ø> (ø)
src/data_morph/shapes/lines/high_lines.py	100.00% <ø> (ø)
src/data_morph/shapes/lines/horizontal_lines.py	100.00% <ø> (ø)
src/data_morph/shapes/lines/rectangle.py	100.00% <ø> (ø)
src/data_morph/shapes/lines/slant_down.py	100.00% <ø> (ø)
... and 16 more

... and 1 file with indirect coverage changes

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