Reformat model

[wanghan-iapcm]

• reformat model to use the output-def to translate the output of the fitting net to the output of the model. we do
  • reduction
  • autodiff
  • map extended variables to local (communicate)
• split the model to atomic model and model. developers implement the atomic model. the model is made from atomic model by the output definition.
• UTs should pass when fix: some issue of the output def  deepmodeling/deepmd-kit#3152 is merged.