Feat: Add AssignNullCoalescingToCoalesceEqualFixer (part of #94)

Author: OndraM

Diff for: tests/Integration/Fixtures/NewPhpFeatures.correct.php.inc

@@ -20,6 +20,9 @@ class NewPhpFeatures
         $dateOrNull = $this->mayReturnDateTimeOrNull();
         $timestamp = $dateOrNull?->getTimestamp(); // RequireNullSafeObjectOperatorSniff
 
+        // AssignNullCoalescingToCoalesceEqualFixer
+        $name = $_GET['name'] ?? 'default';
+
         return $foo;
     }
 

Diff for: tests/Integration/Fixtures/NewPhpFeatures.wrong.php.inc

@@ -23,6 +23,9 @@ class NewPhpFeatures
         $dateOrNull = $this->mayReturnDateTimeOrNull();
         $timestamp = $dateOrNull !== null ? $dateOrNull->getTimestamp() : null; // RequireNullSafeObjectOperatorSniff
 
+        // AssignNullCoalescingToCoalesceEqualFixer
+        $name = isset($_GET['name']) ? $_GET['name'] : 'default';
+
         return $foo;
     }