Introduce qstdweb::bindForever stub for submodule update

The qstdweb::bindForever function will be introduced soon for binding
callbacks with forever lifetime. For now, since submodules have to be
adapted first, introduce a stub function to port qtmultimedia which
uses Promise::make - it will have its interface changed with
relation to bindForever.

Task-number: QTBUG-112296
Change-Id: I578e1633574e11877a8f5ec14d0f00dfd7c766bf
Reviewed-by: Aleksandr Reviakin <aleksandr.reviakin@qt.io>
Reviewed-by: Piotr Wierciński <piotr.wiercinski@qt.io>
Reviewed-by: Lorn Potter <lorn.potter@gmail.com>

src/corelib/platform/wasm/qstdweb_p.h

@@ -196,6 +196,12 @@ namespace qstdweb {
         void Q_CORE_EXPORT all(std::vector<emscripten::val> promises, PromiseCallbacks callbacks);
     };
 
+    template<class F>
+    decltype(auto) bindForever(F wrappedCallback)
+    {
+        return wrappedCallback;
+    }
+
     inline emscripten::val window()
     {
         static emscripten::val savedWindow = emscripten::val::global("window");