[RM-8381] [parameters] template_dir is not always required

Created on 2023-10-04 15:02:18 by Didier Vibert. % Done: 100

MR: https://gitlab.lam.fr/CPF/cpf-redshift/-/merge_requests/551

template_dir parameters should not be required in general

it is required with the following solvers only: templateFittingSolve, templateCombinatonSolve and LineModelSolve if spectrumcomponent is tplfit* (tplfit or tplfitauto)