Add variants of process plugins with handle_multiples set to false

Hurray!

Here's the comment for the info alter, the example being identical to what is covered in the test.

/**
 * Create :foreach process plugin variants that do not handle multiples.
 *
 * For example, if the my_array is an array [4, 2]...
 *
 * @code
 * my_dest:
 *   plugin: evaluate_condition
 *   condition: greater_than(3)
 *   source: my_array
 * @endcode
 *
 * will result in my_dest being TRUE since any array is greater than 3.
 *
 * However...
 *
 * @code
 * my_dest:
 *   plugin: evaluate_condition:foreach
 *   condition: greater_than(3)
 *   source: my_array
 * @endcode
 *
 * will result in my_dest being [TRUE, FALSE] since 4 is greater than 3 while
 * 2 is less than three.
 *
 * Implements hook_migrate_process_info_alter().
 */

Automatically closed - issue fixed for 2 weeks with no activity.