This action causes the assets Caldera Forms loads in the post editor to be enqueued. This action was added in Caldera Forms 1.7.3.
This action should always be used at the caldera_forms_admin_pre_enqueue hook. Using it before then is likely to cause undesirable consequences.
For more information and complete code examples:
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.