Add udev-hid-bpf install

This installs the bpf.o and a corresponding udev rule. Unlike our default setup this udev rule doesn't use the hwdb, it uses the KERNEL property to match on. Usually udev rules are harder to maintain but in this case the goal is to install a single udev rule for a single file, so we're all good.

The lib/firmware path honors the given --prefix (if any, otherwise it defaults to the compiled one). The udev rule is always placed in /etc/ because there are very few use-cases where that isn't the right place to put it.

Closes #10 (closed)