N°3867 Fix "Invalid configuration: Stmt_Expression is forbidden in line 10" error when saving valid config in configuration editor

Now this is tested in \ConfigValidator\iTopConfigAstValidatorTest

datamodels/2.x/itop-config/src/Validator/ConfigNodesVisitor.php

@@ -44,6 +44,7 @@ class ConfigNodesVisitor extends NodeVisitorAbstract
 			Node\Expr\PreDec::class,
 			Node\Expr\PreInc::class,
 			Node\Expr\Print_::class,
+			Node\Stmt\Expression::class,
 			Node\Expr\Ternary::class,
 			Node\Expr\UnaryMinus::class,
 			Node\Expr\UnaryPlus::class,