Add support for logging MultiTaskWrapper in lightning.

[SkafteNicki]

What does this PR do?

Fixes #2193
Will allow this wrapper (which is a specialized version of MetricCollection) to be logged directly through log_dict.

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• Did you write any new necessary tests?

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📚 Documentation preview 📚: https://torchmetrics--2213.org.readthedocs.build/en/2213/

[codecov]

Codecov Report

Merging #2213 (559183d) into master (28ac2b2) will decrease coverage by 49%.
Report is 1 commits behind head on master.
The diff coverage is 40%.

Additional details and impacted files

@@           Coverage Diff            @@
##           master   #2213     +/-   ##
========================================
- Coverage      87%     38%    -49%     
========================================
  Files         293     293             
  Lines       16414   16423      +9     
========================================
- Hits        14270    6201   -8069     
- Misses       2144   10222   +8078