Action that runs before Caldera Forms loads processors via the caldera_forms_get_form_processors filter. This action is used to load processors that use the Caldera_Forms_Processor_Processor class.
Creating Caldera Forms Processors Using The Caldera_Forms_Processor_Processor Class
Where Does This Code Go?
When using WordPress hooks to customize Caldera Forms or other plugins you should not modify the plugin files, or you will lose your changes when you update the plugin. Instead you should create a small plugin to hold the custom code. It's easy, learn how here.
Technically you can add the custom code to your theme's functions.php, but then you will not be able to change your theme and keep these customizations.