evdev: add internal tagging system

evdev: add internal tagging system

For conditional touchpad disabling we need two pieces of knowledge: is the
device an internal touchpad and is another device an external mouse-like
device. For that use-case it's enough to tag any device that's on USB and
Bluetooth with pointer capabilities as external mouse. A more complex can be
done when needed.

The tag function is part of the dispatch interface (to save on udev code) and
called before the caller is notified about the new device, i.e. the device is
fully configured by the time it needs to be tagged, and other devices can rely
on the tags being assigned by the time they get notified about the new device.

Signed-off-by: Peter Hutterer <peter.hutterer@who-t.net>
Reviewed-by: Hans de Goede <hdegoede@redhat.com>