PHP 8.2 | Squiz/LowercaseClassKeywords: add support for readonly classes/properties

Includes unit test.

Ref:
* https://wiki.php.net/rfc/readonly_properties_v2
* https://wiki.php.net/rfc/readonly_classes

Author: jrfnl

src/Standards/Squiz/Sniffs/Classes/LowercaseClassKeywordsSniff.php

@@ -29,6 +29,7 @@ public function register()
         $targets[] = T_IMPLEMENTS;
         $targets[] = T_ABSTRACT;
         $targets[] = T_FINAL;
+        $targets[] = T_READONLY;
         $targets[] = T_VAR;
         $targets[] = T_CONST;
 

src/Standards/Squiz/Tests/Classes/LowercaseClassKeywordsUnitTest.inc

@@ -5,7 +5,7 @@ Interface MyInterface {}
 Trait MyTrait {}
 Enum MyEnum IMPLEMENTS Colorful {}
 
-class MyClass
+ReadOnly class MyClass
 {
     Var $myVar = null;
     Const myConst = true;

src/Standards/Squiz/Tests/Classes/LowercaseClassKeywordsUnitTest.inc.fixed

@@ -5,7 +5,7 @@ interface MyInterface {}
 trait MyTrait {}
 enum MyEnum implements Colorful {}
 
-class MyClass
+readonly class MyClass
 {
     var $myVar = null;
     const myConst = true;

src/Standards/Squiz/Tests/Classes/LowercaseClassKeywordsUnitTest.php

@@ -31,6 +31,7 @@ public function getErrorList()
             4  => 1,
             5  => 1,
             6  => 2,
+            8  => 1,
             10 => 1,
             11 => 1,
             14 => 1,