Enable no_useless_nullsafe_operator

[paulbalandan]

Description

$ vendor/bin/php-cs-fixer describe no_useless_nullsafe_operator   
Description of no_useless_nullsafe_operator rule.
There should not be useless `null-safe-operators` `?->` used.

Fixing examples:
 * Example #1.
   ---------- begin diff ----------
   --- Original
   +++ New
   @@ -1,7 +1,7 @@
    <?php
    class Foo extends Bar
    {
        public function test() {
   -        echo $this?->parentMethod();
   +        echo $this->parentMethod();
        }
    }

   ----------- end diff -----------

Checklist:

• Securely signed commits
• Component(s) with PHPDoc blocks, only if necessary or adds value
• Unit testing, with >80% coverage
• User guide updated
• Conforms to style guide

[MGatner]

Happy to see this one didn't trigger any changes! Null-safe operator is the new empty(): suspicious at best. Well, it would be if empty() weren't still alive and well 😤