Support BIDS-URIs

[effigies]

In an effort to unify the disparate ways of encoding within-dataset paths and remove ambiguity, BIDS-URIs were introduced. You can now end up with IntendedFor = ['bids::sub-01/func/sub-01_task-rest_bold.nii.gz'] where previously you would have had IntendedFor = ['func/sub-01_task-rest_bold.nii.gz'].

As a roadmap:

• Handle within-dataset URIs (bids::*) for IntendedFor and any other field where we may support linking files
• Parse the DatasetLinks field from dataset description; if x exists in DatasetLinks and is in a loaded dataset (e.g., a derivative), then bids:x:* URIs should resolve to existing files.

[Remi-Gau]

tempted to start trying implementing this

just to check: URI resolution should be done when the layout is created and not when it is queried, right? (if my question makes sense)