Insure that Web pages are deleted before the Web Profile to avoir error messages (#3845)

When exiting, GC complains that the Web Profile is released before Web pages that refer to it with the message: "Release of profile requested but WebEnginePage still not deleted. Expect troubles !".
The Web pages are now released explicitly in the destructor to insure that they are freed earlier than the Profile.
Fixes #3844

src/Cloud/OAuthDialog.cpp

@@ -203,6 +203,12 @@ OAuthDialog::OAuthDialog(Context *context, OAuthSite site, CloudService *service
     }
 }
 
+OAuthDialog::~OAuthDialog()
+{
+  if (view) delete view->page();
+  delete view;  // view was constructed without a parent to delete it
+}
+
 // just ignore SSL handshake errors at all times
 void
 OAuthDialog::onSslErrors(QNetworkReply *reply, const QList<QSslError>&)