cubicweb #2543949 [uihelper] transform uihelper functions into uicfg objects methods [done]

This comes on top of the transformation of uicfg configuration into selectable objects.

prioritynormal
typeenhancement
done in3.16.0
load1.000
load left0.000
closed by#5a394fc419b4 [web/uihelper,uicfg] transform uihelper functions into uicfg objects methods (closes #2543949)