How to hook into field creation (form successfully processed)? I need to act after field has been created (new db table).
Actually I need to use data from the first field form: 
field-ui-field-storage-add-form
So ideally I need to hook on this form being successfully processed (and its data).
Is there any way of achieving it?
Something like old hook_field_storage_create_field
Field storage configs and field configs are config entities hand have the standard hook_ENTITY_TYPE_presave/insert/update/delete() hooks. 

/**
 * Implements hook_ENTITY_TYPE_insert() for 'field_storage_config'.
 */
function comment_field_storage_config_insert(FieldStorageConfigInterface $field_storage) {
}