Vento RustDesk backend

An optional plugin for Vento, adding support for RustDesk.

* Hardware-accelerated VP8, VP9, AV1, H.264, and H.265 (where supported by the server and client).
* Multi-monitor support.
* Supports direct or rendezvous connections.

This app must be used with a matching Vento version. It does not have its own launcher icon, and is accessible via the main app.

* Update protocol to 3d6fb2c.