cubicweb-seda #13751394 don't specify URI/filename on attachment [validation pending]

export them automatically in the XSD

prioritynormal
typeenhancement
done in0.4.0
load left0.000
closed by#78b3929471cb [code gen] Skip URI/filename on Attachment, reintroduce Filename on BinaryDataObject
patch[code gen] Skip URI/filename on Attachment, reintroduce Filename on BinaryDataObject [applied]