ENH: Add circle annotation support

[MartinThoma]

See #107

[codecov]

Codecov Report

Base: 91.86% // Head: 91.87% // Increases project coverage by +0.00% 🎉

Coverage data is based on head (647f5f2) compared to base (c293b95).
Patch coverage: 100.00% of modified lines in pull request are covered.

Additional details and impacted files

@@           Coverage Diff           @@
##             main    #1556   +/-   ##
=======================================
  Coverage   91.86%   91.87%           
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  Files          33       33           
  Lines        6124     6130    +6     
  Branches     1208     1210    +2     
=======================================
+ Hits         5626     5632    +6     
  Misses        322      322           
  Partials      176      176           

Impacted Files	Coverage Δ
pypdf/generic/_annotations.py	97.61% <100.00%> (+0.18%)	⬆️

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[MartinThoma]

@pubpub-zz / @MasterOdin Should we call it "ellipse" instead of circle? (similar to the fact that we called it "square" instead of rectangle? https://pypdf.readthedocs.io/en/latest/modules/AnnotationBuilder.html#pypdf.generic.AnnotationBuilder.rectangle

[pubpub-zz]

@pubpub-zz / @MasterOdin Should we call it "ellipse" instead of circle? (similar to the fact that we called it "square" instead of rectangle? https://pypdf.readthedocs.io/en/latest/modules/AnnotationBuilder.html#pypdf.generic.AnnotationBuilder.rectangle

ellipse is more consistent with rectangle. we must not forget the note:
This method uses the "circle" annotation type of the PDF format.

[MasterOdin]

I agree that ellipse is more consistent with the existing rectangle method and that like using rectangle instead of square, using ellipse instead of circle is more mathematically accurate as you cannot draw a circle where the distance between the centre and the perimeter is different at some point in the circle, as then it wouldn't be a circle.

All circles are ellipses, but not all ellipses are circles.