Add popup WebView2 window method

Currently we can use WebView2 control in WPF, UWP, Windows App SDK, etc. to load a web page embedded. It could be better if provide a method to popup a window with WebView2 and other default components like js function window.open() does but it is in host app side, such as following. So that we can call this method when we need popup a web window and no more customization requirement.

namespace Microsoft.Web.WebView2.Core;
public sealed class CoreWebView2
{
+  public static Window OpenWindow(string uri, CoreWebView2WindowFeatures windowFeatures = null);
+  public static Window OpenWindowToString(string htmlContent, CoreWebView2WindowFeatures windowFeatures = null);
  // Other members.
}

AB#38444170