List datasets more info

[MalinAhlberg]

Related issue(s) and PR(s)
This PR closes #438 .

Description
sda-cli list -datasets will print number of files and dataset size:

DatasetID                                	 Files 	 Size
https://doi.example/ty009.sfrrss/600.45asasga 	 3 	 3.1 MB
https://doi.example/ty009.sfrrss/Dataset         1 	 1.1 MB

How to test
From the root folder run the setup script:

bash .github/integration/setup/setup.sh

(note to future self: if it does not work, remove all containers and run docker volume rm -f $(docker volume ls -f "dangling=true")).
Then run:

./sda-cli list -config testing/s3cmd-download.conf -datasets -url http://localhost:8080 

And get

DatasetID                                	 Files 	 Size
https://doi.example/ty009.sfrrss/600.45asasga 	 3 	 3.1 MB

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Codecov Report

Attention: Patch coverage is 0% with 19 lines in your changes missing coverage. Please review.

Project coverage is 38.79%. Comparing base (d24ea15) to head (d9de7b2).

Files with missing lines	Patch %	Lines
list/list.go	0.00%	19 Missing ⚠️

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Additional details and impacted files

@@            Coverage Diff             @@
##             main     #444      +/-   ##
==========================================
- Coverage   39.04%   38.79%   -0.25%     
==========================================
  Files          11       11              
  Lines        1903     1915      +12     
==========================================
  Hits          743      743              
- Misses       1048     1060      +12     
  Partials      112      112              

Flag	Coverage Δ
unittests	38.79% <0.00%> (-0.25%)	⬇️

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[aaperis]

LGTM, I also like the "note to self" on the description 😄