community/gnome-boxes: fix box creation by enabling smartcard support in qemu/spice

This MR adds a new package - libcacard, enables smartcard support in qemu, spice and spice-gtk and rebuilds gnome-boxes against the updates spice-gtk, just in case.

Fixes #12998 (closed). See that issue for a more detailed write-up of the problem. TL;DR: review-page.vala:32: Box setup failed: Failed to create domain: unsupported configuration: this QEMU binary lacks smartcard passthrough mode support

Important note: the new package (libcacard) has to be in main, as it's used by spice which is also in main. Not really sure what the general consensus on adding a new package to main is; perhaps this is going a bit too far, in which case please let me know.