Feat: Add LongToShorthandOperatorFixer (part of #94)

Author: OndraM

ecs.php

@@ -93,6 +93,7 @@
 use PhpCsFixer\Fixer\NamespaceNotation\NoLeadingNamespaceWhitespaceFixer;
 use PhpCsFixer\Fixer\Operator\BinaryOperatorSpacesFixer;
 use PhpCsFixer\Fixer\Operator\ConcatSpaceFixer;
+use PhpCsFixer\Fixer\Operator\LongToShorthandOperatorFixer;
 use PhpCsFixer\Fixer\Operator\NewWithParenthesesFixer;
 use PhpCsFixer\Fixer\Operator\NoSpaceAroundDoubleColonFixer;
 use PhpCsFixer\Fixer\Operator\ObjectOperatorWithoutWhitespaceFixer;
@@ -310,6 +311,8 @@
             NoLeadingNamespaceWhitespaceFixer::class,
             // Binary operators should be surrounded by exactly one single space.
             BinaryOperatorSpacesFixer::class,
+            // Shorthand notation for operators should be used if possible.
+            LongToShorthandOperatorFixer::class,
             // There must be no space around scope resolution double colons
             NoSpaceAroundDoubleColonFixer::class,
             // All instances created with new keyword must be followed by parentheses.

tests/Integration/Fixtures/Basic.correct.php.inc

@@ -61,6 +61,12 @@ class Basic extends AbstractBasic implements InterfaceFromThisNamespace // Fully
             $baz = implode(',', ['foo', 'bar']);
         }
 
+        $i = 3;
+        $i += 6; // LongToShorthandOperatorFixer
+        $i *= 2; // LongToShorthandOperatorFixer
+        $text = 'foo';
+        $text .= 'bar'; // LongToShorthandOperatorFixer
+
         // HeredocIndentationFixer
         $heredoc = <<<HEREDOC
             This is a

tests/Integration/Fixtures/Basic.wrong.php.inc

@@ -53,6 +53,12 @@ class Basic extends \Some\Other\Namespace\AbstractBasic implements \Lmc\CodingSt
             $baz = join(',', ['foo', 'bar']);
         }
 
+        $i = 3;
+        $i = $i + 6; // LongToShorthandOperatorFixer
+        $i = $i * 2; // LongToShorthandOperatorFixer
+        $text = 'foo';
+        $text = $text . 'bar'; // LongToShorthandOperatorFixer
+
         // HeredocIndentationFixer
         $heredoc = <<<HEREDOC
 This is a