Upgrade from Smarty 3 to Smarty 4 to be PHP 8.1 compatible

Remove all Smarty4 dedicated tests, all are done in the same test file
like before

www/lib/smarty-4.1.0/libs/sysplugins/smartycompilerexception.php

@@ -0,0 +1,45 @@
+<?php
+
+/**
+ * Smarty compiler exception class
+ *
+ * @package Smarty
+ */
+class SmartyCompilerException extends SmartyException
+{
+    /**
+     * @return string
+     */
+    public function __toString()
+    {
+        return ' --> Smarty Compiler: ' . $this->message . ' <-- ';
+    }
+
+    /**
+     * @param int $line
+     */
+    public function setLine($line)
+    {
+        $this->line = $line;
+    }
+    /**
+     * The template source snippet relating to the error
+     *
+     * @type string|null
+     */
+    public $source = null;
+
+    /**
+     * The raw text of the error message
+     *
+     * @type string|null
+     */
+    public $desc = null;
+
+    /**
+     * The resource identifier or template name
+     *
+     * @type string|null
+     */
+    public $template = null;
+}