Support IDispatchEx for host objects

[champnic]

@champnic do you know if Webview2 will use the IDispatchEx interface if present? I'm seeing some issues with the current implementation because IDispatch doesn't allow specifying this in a call. Therefore, I have to pass the object as the first parameter. Let's say my host object is just an array of 4 string. The below code is what I have to use to properly call the Has() and Pop() methods on the array currently.

(async function() {
    const arr = window.chrome.webview.hostObjects.AHK;

    console.log(await arr.Has(arr, 1));
    console.log(await arr.Pop(arr));
})();

Originally posted by @kczx3 in #513 (comment)

AB#32539019