When bridging 32-bit/64-bit plugins on Windows, the plugin is hosted in
an auxilliary process, and the plugin's editor is embedded into an HWND
owned by a different process (the plugin host).

Previously, the `isForegroundProcess` check would fail for bridged
plugins, because the foreground window may belong to the DAW, rather
than to the auxilliary hosting process.

This patch adds an additional check, to find whether the same process
owns both the foreground window, and the window which embeds the
PopupMenu's target component. In this case, we avoid immediately
dismissing the PopupMenu.