feat: new-design GPG window

[WolfgangKurz]

---

Find old-style (CROSVM_1 class window) first.
If failed, find new-style (HwndWrapper[DefaultDomain;;....] class window as wrapper).

[WolfgangKurz]

Fixes #15 and #16.
Those issues were caused by a failure to acquire the handle for the new-design GPG window.

[ACK72]

Thanks for the help. I've merged the pull request into the main branch.
By the way, I think it's better to simply print out potential errors (only) in this simple program.