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/plugins/modifiercompiler.strip.php

@@ -0,0 +1,30 @@
+<?php
+/**
+ * Smarty plugin
+ *
+ * @package    Smarty
+ * @subpackage PluginsModifierCompiler
+ */
+/**
+ * Smarty strip modifier plugin
+ * Type:     modifier
+ * Name:     strip
+ * Purpose:  Replace all repeated spaces, newlines, tabs
+ *              with a single space or supplied replacement string.
+ * Example:  {$var|strip} {$var|strip:"&nbsp;"}
+ * Date:     September 25th, 2002
+ *
+ * @link   https://www.smarty.net/manual/en/language.modifier.strip.php strip (Smarty online manual)
+ * @author Uwe Tews
+ *
+ * @param array $params parameters
+ *
+ * @return string with compiled code
+ */
+function smarty_modifiercompiler_strip($params)
+{
+    if (!isset($params[ 1 ])) {
+        $params[ 1 ] = "' '";
+    }
+    return "preg_replace('!\s+!" . Smarty::$_UTF8_MODIFIER . "', {$params[1]},{$params[0]})";
+}