feat(ui/MSALoginDialog): use libqrencode for qr codes

`qrcodegen` isn't available in most repositories, package discovery
scripts for it are maintained in a different repository, and they are
bugged for Windows at least. This basically forces us into vendoring it,
which isn't cool; libqrencode seems like viable alternative used by many
more apps

Signed-off-by: Seth Flynn <getchoo@tuta.io>

vcpkg.json

@@ -3,6 +3,7 @@
     "bzip2",
     "cmark",
     { "name": "ecm", "host": true },
+    "libqrencode",
     { "name": "pkgconf", "host": true },
     "tomlplusplus",
     "zlib"