Add ability to filter qubes input devices with udev rules

This is similar to the workaround suggested in
QubesOS/qubes-issues#3604, but lacks the UX integration I would expect
to resolve the issue.

qubes-rpc/qubes-input-proxy.rules

@@ -8,6 +8,9 @@ ENV{ID_PATH}=="platform-*", GOTO="qubes_input_proxy_end"
 # tag virtual input device so it can be identified when qubes-input-trigger is launched by /etc/xdg/autostart/qubes-input-trigger.desktop
 ATTRS{name}=="Qubes Virtual Input Device", TAG="qubes-virtual-input-device"
 
+# skip devices which are disabled for libignore
+ENV{LIBINPUT_IGNORE_DEVICE}=="1", GOTO="qubes_input_proxy_end"
+
 # skip virtual input device created by gui agent
 ATTRS{name}=="Qubes Virtual Input Device", GOTO="qubes_input_proxy_end"