title: window.external.[MyFunction] does not work with Outlook VSTO project
body: <p>I have a VSTO Outlook project that's open external VisuaForce page from Salesforce environment <code>using &quot;System.Windows.Forms.WebBrowser&quot;</code>.
  VF page use JS method <code>window.external.BrowserSubmitFile(jsondata, bSingleFiling) whereBrowserSubmitFile()</code> is C# method in Outlook project to exchange information between Salesforce and Outlook.</p>
  <p>But now the project was updated for using WebView2 and when trying to call the C# method from the VF page I get this error: <code>&quot;TypeError: window.external.BrowserSubmitFile is not a function&quot;</code></p>
  <p>I found in internet, that it could be because I am opening it in browser window, not inside Office app.
  Question: how to open web pages inside Office app using WebView2?</p>