PHP 8.2 | Generic/LowerCaseType: allow for stand-alone true/false/null

As of PHP 8.2, `true`, `false` and `null` will be allowed as stand-alone types.
The `true` and the `false` types are allowed to be nullable, the `null` type is not (but that's not the concern of the sniff).
Also see: https://3v4l.org/ZpfID

This commit adjusts the sniff to take `true` into account. `false` and `null` were already handled due to these previously already being allowed in union types.

Includes unit tests.

Refs:
* https://wiki.php.net/rfc/null-false-standalone-types
* https://wiki.php.net/rfc/true-type

Author: jrfnl

src/Standards/Generic/Sniffs/PHP/LowerCaseTypeSniff.php

@@ -37,6 +37,7 @@ class LowerCaseTypeSniff implements Sniff
         'mixed'    => true,
         'static'   => true,
         'false'    => true,
+        'true'     => true,
         'null'     => true,
         'never'    => true,
     ];

src/Standards/Generic/Tests/PHP/LowerCaseTypeUnitTest.inc

@@ -92,3 +92,5 @@ function intersectionReturnTypes ($var): \Package\ClassName&\Package\Other_Class
 
 $arrow = fn (int $a, string $b, bool $c, array $d, Foo\Bar $e) : int => $a * $b;
 $arrow = fn (Int $a, String $b, BOOL $c, Array $d, Foo\Bar $e) : Float => $a * $b;
+
+$cl = function (False $a, TRUE $b, Null $c): ?True {}

src/Standards/Generic/Tests/PHP/LowerCaseTypeUnitTest.inc.fixed

@@ -92,3 +92,5 @@ function intersectionReturnTypes ($var): \Package\ClassName&\Package\Other_Class
 
 $arrow = fn (int $a, string $b, bool $c, array $d, Foo\Bar $e) : int => $a * $b;
 $arrow = fn (int $a, string $b, bool $c, array $d, Foo\Bar $e) : float => $a * $b;
+
+$cl = function (false $a, true $b, null $c): ?true {}

src/Standards/Generic/Tests/PHP/LowerCaseTypeUnitTest.php

@@ -67,6 +67,7 @@ public function getErrorList()
             82 => 2,
             85 => 1,
             94 => 5,
+            96 => 4,
         ];
 
     }//end getErrorList()