[Command] Added LockHelper

| Q             | A
| ------------- | ---
| Doc fix?      | no
| New docs?     | yes https://github.com/symfony/symfony/pull/10475
| Applies to    | Symfony version 2.6+
| Fixed tickets | -
I would change this to something like: ```You can pass an optional ``$blocking`` argument to the ``lock()`` method, which defaults to ``false``. If this is set to ``true``, the PHP code will not be executed further unless the lock is released by another process.```