cubicweb #2741963 uicfg: the set_fields_order helper does only impose an order on forms [validation pending]

We want it for primary views (at least).

prioritynormal
typebug
done in3.18.0
load0.300
load left0.000
closed by#099a3a33eaaa [uicfg] give a set_fields_order method to the primary view display control
patch[uicfg] give a set_fields_order method to the primary view display control [applied]