qmljs: correctly handle js string templates

In most cases we do want to visit the expressions in a function
template. Changing its accept0 would force those not wanting to visit
it to iterate on the templates (currently a linked list), so we add a
visit method explicitly visiting the expression in all the needed
places.

Fixes: QTCREATORBUG-21869
Change-Id: I47733544bfd32eec357810b97242608b8f7de572
Reviewed-by: Qt CI Bot <qt_ci_bot@qt-project.org>
Reviewed-by: Fabian Kosmale <fabian.kosmale@qt.io>
Reviewed-by: Henning Gründl <henning.gruendl@qt.io>

src/libs/qmljs/jsoncheck.h

@@ -51,6 +51,7 @@ private:
     bool preVisit(AST::Node *) override;
     void postVisit(AST::Node *) override;
 
+    bool visit(AST::TemplateLiteral *ast) override;
     bool visit(AST::ObjectPattern *ast) override;
     bool visit(AST::ArrayPattern *ast) override;
     bool visit(AST::NullExpression *ast) override;