Yubico - Yubikey support

[tcodes0]

Thoughts on yubikey support and similar hardware solutions? Thanks for this amazing pw manager!

[perry-mitchell]

We'd love Yubikey support, though I believe neither @sallar nor myself are experts in integrating them. I own a Yubikey but haven't yet used it - but this just means that I could certainly help test any contributions. I don't yet have the bandwidth to add support myself, but perhaps one day. Otherwise I'd be happy with someone contributing basic support.

Such a PR would need to add some common interface support to the core library and perhaps some special integration in the desktop app.