qml | Fix let/const variables formatting

Change-Id: Ia2a4ee482e84a6c24abea7ea6fe05925eee11d1d
Reviewed-by: Thomas Hartmann <thomas.hartmann@qt.io>

src/libs/qmljs/qmljsreformatter.cpp

@@ -914,7 +914,8 @@ protected:
 
     bool visit(VariableStatement *ast) override
     {
-        out("var ", ast->declarationKindToken);
+        out(ast->declarationKindToken);
+        out(" ");
         accept(ast->declarations);
         return false;
     }

tests/auto/qml/reformatter/jssyntax.js

@@ -1,6 +1,10 @@
 var x
 var y = 12
 
+var a_var = 1
+let a_let = 2
+const a_const = 3
+
 function foo(a, b) {
     x = 15
     x += 4