RecipeRunner::processInstall() installs modules one by one

Note we need to think about \Drupal\Core\Recipe\RecipeRunner::toBatchOperationsInstall() too

It's likely this change will result in quite a bit of refactoring.

The tricky bit here will be

    // Disable configuration entity install but use the config directory from
    // the module.
    \Drupal::service('config.installer')->setSyncing(TRUE);
    $default_install_path = \Drupal::service('extension.list.module')->get($module)->getPath() . '/' . InstallStorage::CONFIG_INSTALL_DIRECTORY;
    // Allow the recipe to override simple configuration from the module.
    $storage = new RecipeOverrideConfigStorage(
      $recipeConfigStorage,
      new FileStorage($default_install_path, StorageInterface::DEFAULT_COLLECTION)
    );

@phenaproxima suggested wrapping all the config from all the modules together. This might work because modules cannot have conflicting config - we have the PreExistingConfiguration exception that handles that. I'm concerned that it might not work because that when you install the first module it'd discover all the configuration from the modules that are yet to be installed. Not sure how that's going to work out.