Allow the comparitor to set individual components from the config

Chain remapping can be done using components in the configuration files, but thay also override the histogram and panel settings.

These changes allow the chain remapping components to be used and still use the default setting for the histograms if the histograms are not in the config file.

This changes to this file are for a standalone executable and not as part of code to run as part of the athena executable. It is not used by any part of any required CI execution tests, so the only test that is valid is the actual building - this code is not executed at all, during any of the CI execution tests, and none of those tests depend on this code.