New method of finding parent/child doesn't work for apps without top level HWNDs

[david-risney]

The PowerToys app has a tool to show file previews in Explorer.exe using WebView2. It runs in prevhost.exe and doesn't have its own top level HWND but rather seems to be parented to explorer's.

Should add a checkbox to try harder to find webview2 runtimes and enum all top level windows not limiting to those of webview2 host apps and also check parent/child pid