[RM-8229] [parameters] refactor continuumfit.priors and tplratio.priors

Created on 2023-08-24 13:04:12 by Didier Vibert. % Done: 0

in the current version the @CPriorHelper@ class is instantiated using @XXX.priors.catalog_dirpath@ for reading the calib files.
if the @catalog_dirpath@ is not found (eg an empty string) then a warning is issued and the handling of the @ CPriorHelper@ is deactivated.

TODO:
1. create a bool param for activating the priors (or use the presence of the section as a required activation)
2. do not try to read the parameter of the section (in case of a boolean)
3. transfer the I/O to python code ?