[solidago] Implement get_individual_scores & get_collective_scores

[NatNgs]

Description

Implemented Solidago pipeline input get_individual_scores and get_collective_scores functions

• Added user_id and entity_id to dataframe, as it was done for users and comparisons dataframes
• Added Unit tests in test_pipeline.py (seems to be the good place as per the name)
• Initially based on master, rebased to branch neurips24 as per requested

Checklist

• I added the related issue(s) id in the related issues section (if any)
  • if not, delete the related issues section
• I described my changes and my decisions in the PR description
• I read the development guidelines of the CONTRIBUTING.md
• The tests pass and have been updated if relevant
• The code quality check pass

[NatNgs]

Things to improve I just found:

• Some columns are formatted as float but can be formatted as int (collective_scores.users, collective_scores.comparisons)
• Certainly improvements to be made to get to the same result with more clever pandas functions I don't know

[amatissart]

Some columns are formatted as float but can be formatted as int (collective_scores.users, collective_scores.comparisons)

@NatNgs This is actually due do how pandas converts integers to floats when there are missing values (NaN) in the columns created by the "left join". Specifically some entities that are present in the collective scores may not appear in "comparisons.csv" (this is the case when the video has only been compared privately).

I tried to make that more explicit in another branch. See PR #2022 targeting this branch and the comments in the changes. Let me know if you have other pending work on this branch.