IntendedFor and Sources with only relative path to dataset root is now deprecated

[SamGuay]

In the specs, it is mentioned that:

Using forward-slash separated paths relative to the participant subdirectory is DEPRECATED.

So that means IntendedFor and Sources should get a list of files with the paths specified using BIDS URIs as value instead of relative paths to root dataset only.

In dcm2bids context, it seems that we just need to add bids:: in front of the path.