[PHP 8.0] Add str_starts_with - rule #500 🎉🎉🎉

[TomasVotruba]

• Ref [PHP 8.0] [Meta]  #3127
• Ref [PHP 8.0] Add str_starts_with and str_ends_with #3221

 class SomeClass
 {
     public function run()
     {
-        $isMatch = substr($haystack, 0, strlen($needle)) === $needle;
+        $isMatch = str_starts_with($haystack, $needle);

-        $isNotMatch = substr($haystack, 0, strlen($needle)) !== $needle;
+        $isMatch = ! str_starts_with($haystack, $needle);
     }
 }