Add confidence scores when extended_summary=True in MeanAveragePrecision

[SkafteNicki]

What does this PR do?

Fixes #2202

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• Did you make sure to update the docs?
• Did you write any new necessary tests?

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📚 Documentation preview 📚: https://torchmetrics--2212.org.readthedocs.build/en/2212/

[codecov]

Codecov Report

Merging #2212 (01e9855) into master (9dd199a) will decrease coverage by 50%.
The diff coverage is n/a.

Additional details and impacted files

@@           Coverage Diff            @@
##           master   #2212     +/-   ##
========================================
- Coverage      87%     37%    -50%     
========================================
  Files         293     293             
  Lines       16425   16425             
========================================
- Hits        14278    6031   -8247     
- Misses       2147   10394   +8247