[ENH] update data dictionnary with the actual list of Levels present in TSV files.

[Remi-Gau]

You need this code to do:

Given a tsv file, it should generate / update the data dictionary, especially the Levels object so that the user can then easily fill in what each level corresponds to.

[CerenB]

related to that, this is done, no?
Now there's a lot of info in _bold.tsv file. Is it all bids-valid? (I failed at bids-validator for another reason, so not sure if having info in bold.tsv is valid or not. )