Config exporter.php

<?php
use Drupal\Core\Extension\ExtensionDiscovery;

// IMPORTANT!
// Uncomment $settings['extension_discovery_scan_tests'] = TRUE; in settings.php
// to include test modules.

//$config_entity_type_id = drush_prompt('Entity type ID?');
//$config_entity_provider = drush_prompt('Entity type provider? (leave blank if core)');

$config_entity_type_id = 'view';
$config_entity_provider = 'views';


// Ensure provider is installed.
if ($config_entity_provider) {
  \Drupal::moduleHandler()->install(array($config_entity_provider));
}

$config_entity_type = \Drupal::entityManager()->getDefinition($config_entity_type_id);
$entity_storage = \Drupal::entityManager()->getStorage($config_entity_type_id);

$listing = new ExtensionDiscovery(\Drupal::root());
$modules = $listing->scan('module');

foreach ($modules as $module) {
  $extension_path = $module->getPath();

  // If the extension provides configuration schema clear the definitions.
  if (is_dir($extension_path . '/' . \Drupal\Core\Config\InstallStorage::CONFIG_INSTALL_DIRECTORY)) {
    $install_storage = new \Drupal\Core\Config\FileStorage($extension_path . '/' . \Drupal\Core\Config\InstallStorage::CONFIG_INSTALL_DIRECTORY);
    $entities = $install_storage->listAll($config_entity_type->getConfigPrefix());
    if (count($entities)) {
      // Ensure module is installed.
      \Drupal::moduleHandler()->install(array($module->getName()));
    }
    foreach ($entities as $name) {
      $id = substr($name, strlen($config_entity_type->getConfigPrefix()) + 1);
      $loaded_entity = $entity_storage->load($id);
      $data = $loaded_entity->toArray();
      unset($data['uuid']);
      $config = new \Drupal\Core\Config\Config($name, $install_storage, \Drupal::service('event_dispatcher'), \Drupal::service('config.typed'));
      $config->setData($data)->save();
    }
  }
  if (is_dir($extension_path . '/test_views')) {
    // Ensure module is installed.
    \Drupal::moduleHandler()->install(array($module->getName()));
    $install_storage = new \Drupal\Core\Config\FileStorage($extension_path . '/test_views');
    $entities = $install_storage->listAll($config_entity_type->getConfigPrefix());
    foreach ($entities as $name) {
      if (\Drupal::service('config.storage')->exists($name)) {
        $id = substr($name, strlen($config_entity_type->getConfigPrefix()) + 1);
        $entity_storage->load($id)->delete();
      }
      $entity = $entity_storage->createFromStorageRecord($install_storage->read($name));
      try {
        $entity->save();
      }
      catch (\Exception $e) {
        print "Saving $name has generated the following exception: " . $e->getMessage() . "\n";
        continue;
      }
      $data = $entity->toArray();
      unset($data['uuid']);
      $config = new \Drupal\Core\Config\Config($name, $install_storage, \Drupal::service('event_dispatcher'), \Drupal::service('config.typed'));
      $config->setData($data)->save();
    }
  }
}

Would this work for contrib modules as well?

$listing = new ExtensionDiscovery(\Drupal::root());
$modules = $listing->scan('module');

According to this yes!

Needs \Drupal::moduleHandler()->install => \Drupal::service('module_installer')->install() update