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/docs/programmers/resources.md

@@ -0,0 +1,19 @@
+Resources
+=========
+
+The templates may come from a variety of sources. When you
+[`display()`](./api-functions/api-display.md) or [`fetch()`](./api-functions/api-fetch.md) a template, or
+when you include a template from within another template, you supply a
+resource type, followed by the appropriate path and template name. If a
+resource is not explicitly given, the value of
+[`$default_resource_type`](./api-variables/variable-default-resource-type.md) (default:
+\"file\") is assumed.
+
+## Table of contents
+
+- [File Template Resources](./resources/resources-file.md)
+- [String Template Resources](./resources/resources-string.md)
+- [Stream Template Resources](./resources/resources-streams.md)
+- [Extends Template Resources](./resources/resources-extends.md)
+- [Custom Template Resources](./resources/resources-custom.md)
+