support dcm2niix "Bidsguess"

[yarikoptic]

Tireless @neurolabusc has developed https://github.com/rordenlab/dcm2niix/tree/development/BidsGuess which would populate BidsGuess field in sidecar .json files with dcm2niix's guesses for modality type and entities, e.g.

"BidsGuess": ["anat","_acq-tse2_run-3_PDw"],
"BidsGuess": ["anat","_acq-tse2_run-3_T2w"],

I guess we better make use of this! I see multiple ways

• We already support some placeholders such as bids_subject_session_prefix and bids_subject_session_dir code. We can add dcm2niix_bids_guess_modality and dcm2niix_bids_guess_entities, so some "lazy" heuristic called dcm2niix_guess could just return {bids_subject_session_dir}/{dcm2niix_bids_guess_modality}/{bids_subject_session_prefix}{dcm2niix_bids_guess_entities} and be done
• Provide more detailed breakdown of entities, such as dcm2niix_bids_guess_entity_acq, dcm2niix_bids_guess_entity_run, and dcm2niix_bids_guess_suffix (naming might need to be improved) so heuristics like reproin could selectively make use of them.