Add aggregate argument to retrieval metrics

[SkafteNicki]

What does this PR do?

Fixes #2187

Before submitting

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• Did you read the contributor guideline, Pull Request section?
• Did you make sure to update the docs?
• Did you write any new necessary tests?

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📚 Documentation preview 📚: https://torchmetrics--2220.org.readthedocs.build/en/2220/

[codecov]

Codecov Report

Merging #2220 (bb8a198) into master (245ee24) will decrease coverage by 52%.
The diff coverage is 93%.

Additional details and impacted files

@@           Coverage Diff            @@
##           master   #2220     +/-   ##
========================================
- Coverage      87%     35%    -52%     
========================================
  Files         293     293             
  Lines       16437   16465     +28     
========================================
- Hits        14275    5722   -8553     
- Misses       2162   10743   +8581     

[daturkel]

Incredible, I didn't realize you were even working on this (I had it on my backlog to take a stab at it). Thank you for your help!

[SkafteNicki]

Incredible, I didn't realize you were even working on this (I had it on my backlog to take a stab at it). Thank you for your help!

You are welcome ! sorry for not informing you that I had already implemented it myself :)