Add support for stylus-on-touchscreen devices found on some laptops

My OneMix Pro 3 required this entry in 60-input-id.hwdb:

id-input:modalias:input:b0018v27C6p0113e0100-e0,1,3,kra2F,35,36,39,3A,3B,mlsfw
 ID_INPUT_TABLET=1
 ID_INPUT_TOUCHSCREEN=0

Logs:

• libinput record output: replay
• X.Org log with -logverbose 6: Xorg.0.log
• X.Org log at default verbosity: Xorg.0.log-default
• krita log with bumped input log: klog

Should resolve #486 (Dell Inspiron 15) as well, it might be prudent to @ its reporters

I don't have a classic Wacom tablet, so I haven't tested on one. It should be entirely seamless with how I wrote it, but you know. It'd be great if someone could test there.

Also, i don't think the "libinput requires either or both of them to be present." in the tablet-debugging bit is accurate; this has neither and I just overrode the the detection code at first and it worked pretty well, except for relying on the timer to unset proximity, which didn't pose a problem.