[core]register_process: add a relative_to parameter to store numpy array relative to "r" values and not only "energy"

[pymca/larch] start normalization between the two process. Update display and check values for normalization vs pre_edge

For now this is just comparaison, no internal process is made to make fit the two libraries.

Merge branch 'add_larch_process_orange_contrib' of gitlab.esrf.fr:workflow/xas into add_larch_process_orange_contrib

Add larch process in core

See merge request workflow/xas!11

[core][larch] fix creation of the new secptrum object when overwrite is True in larch process wrappers