Wacom tablet issues

[raingloom <raingloom@riseup.net>]

I'm having trouble properly setting up my Wacom Intuos CTH-480 tablet. 
It is recognized as a tablet and pressure sensitivity is working, but 
the eraser is not recognized as a separate input device. I used it in 
Arch, where it worked flawlessly, so it's not a driver bug.

`libwacom-list-local-devices` shows them, but `xsetwacom --list 
devices` does not.

I think it is a udev issue.

I ran `udevadm info $(libwacom-list-local-devices | grep 'Device node' 
| cut -f 4- -d ' ')` in both Guix and a NixOS VM and in Guix it seems 
to only show a single device, while in Nix it shows 3.

I managed to get the libwacom udev rules in my system config, at least 
I think I did, since the following files exist:

```
/run/booted-system/profile/lib/udev/rules.d/65-libwacom.rules
/run/booted-system/profile/lib/udev/rules.d/wacom.rules
```

Not sure how to proceed. Any tips?