[REF] BIDS : refactor function create_participants_df from bids_utils

[AliceJoubert]

Small refactor of create_participants_df of bids_utils :

Previously :

• Compared BIDS to clinical data
• Adapted to OASIS and ADNI only
• Using dataframes but not the corresponding existing methods

Planned :

• If possible adapt it to all datasets, at least check on dataset if should not be used for it ; ex AIBL has redundant function
• Simplify code loops
• Tests if needed

Maybe in another function :

• Compare BIDS result to initial raw dataset, available for all types of datasets (same as cleaning sessions/subjects)

[NicolasGensollen]

Thanks for starting working on this @AliceJoubert !

I think it might be better to pause this PR a bit while:

• PR [REF] Refactor converters #1140 is merged (I'm confident this can happen soon 🤞 )
• unit tests for this function are added

I know it's hard to start refactoring a piece of code by writing unit tests for the code to be changed, but it is a much safer approach than refactoring first and writing tests afterwards.
Let me know what you think !

[NicolasGensollen]

I don't understand what this means