[ENH] owkaplanmeier: add annotated data output

[JakaKokosar]

Issue

Description of changes

Includes

• Code changes
• Tests
• Documentation

[codecov-commenter]

Codecov Report

Merging #43 (a589e0c) into master (78cda04) will increase coverage by 0.56%.
The diff coverage is 100.00%.

@@            Coverage Diff             @@
##           master      #43      +/-   ##
==========================================
+ Coverage   45.19%   45.76%   +0.56%     
==========================================
  Files          12       12              
  Lines        1166     1180      +14     
==========================================
+ Hits          527      540      +13     
- Misses        639      640       +1     

Impacted Files	Coverage Δ
...contrib/survival_analysis/widgets/owkaplanmeier.py	94.35% <100.00%> (-0.05%)	⬇️

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