StartAttachPubkeyToUserXRD: Runs only for XRD generation where a Magicsig exists for a Profile which is a "person".
@param  Magicsig    $magicsig   crypto stuff related to the profile we're representing
@param  XRD         $xrd        the XRD object which holds all data for the profile we're representing

EndAttachPubkeyToUserXRD: Runs only for XRD generation where a Magicsig exists for a Profile which is a "person". And only if StartAttachPubkeyToUserXRD didn't abort.
@param  Magicsig    $magicsig   crypto stuff related to the profile we're representing
@param  XRD         $xrd        the XRD object which holds all data for the profile we're representing
