Remove HelicityModel.sum_components() method

[redeboer]

HelicityModel.sum_components() is quite sensitive to bugs, because it checks patterns in parameter names and also is not well tested for interference effects and then computes coherent vs incoherent sums based on those names. It would be better to leave it up to the user to set certain coefficients/couplings to zero in the function as lambdified with TensorWaves, so that the summing is guaranteed to be the same as in the total model.