Adds support for array closures in Generic.CodeAnalysis.UnusedFunctionParameter

Related to #2523

Author: michalbundyra

src/Standards/Generic/Sniffs/CodeAnalysis/UnusedFunctionParameterSniff.php

@@ -34,6 +34,7 @@ public function register()
         return [
             T_FUNCTION,
             T_CLOSURE,
+            T_FN,
         ];
 
     }//end register()

src/Standards/Generic/Tests/CodeAnalysis/UnusedFunctionParameterUnitTest.inc

@@ -121,3 +121,5 @@ function something($a) {
 function myCallback($a, $b, $c, $d) {
     return $a * $c;
 }
+
+fn ($a, $b, $c) => $b;

src/Standards/Generic/Tests/CodeAnalysis/UnusedFunctionParameterUnitTest.php

@@ -49,6 +49,7 @@ public function getWarningList()
             106 => 1,
             117 => 1,
             121 => 2,
+            125 => 2,
         ];
 
     }//end getWarningList()