Create a new `OptimWrapper` from `self` with another `layer_groups` but the same hyper-parameters.

def new(self, layer_groups:Collection[nn.Module], split_no_wd:bool=True):
        "Create a new `OptimWrapper` from `self` with another `layer_groups` but the same hyper-parameters."
        opt_func = getattr(self, 'opt_func', self.opt.__class__)
        res = self.create(opt_func, self.lr, layer_groups, wd=self.wd, true_wd=self.true_wd, bn_wd=self.bn_wd)
        res.mom,res.beta = self.mom,self.beta
        return res