Allow for GeneratedBy in any sidecar .json file to collect their provenance

[yarikoptic]

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Your idea

• https://github.com/bids-standard/bids-2-devel/issues/80#issuecomment-2437597659

and reflecting on

• https://github.com/bids-standard/bids-specification/pull/440

for GeneratedBy to be universally adopted at the Dataset level.

To accommodate provenance "per file", e.g. for dcm2niix and alike, we better allow for GeneratedBy at individual file level.