Add PreferStylusOverTouchBlocker and handle multiple devices

We removed PreferStylusOverTouchBlocker previously in order to avoid a
crash. In this CL, we are adding it back in, and handling the case of
input device having "SOURCE_STYLUS", but reporting "finger" tool type.

If there's a stylus event with one of the pointers labeled as 'finger',
let's assume that the device supports simultaneous touch and stylus. For
this situation, simply disable PreferStylusOverTouchBlocker going
forward for these devices, and pass through any events coming from there.

Currently, this happens on emulator. In their touch driver, they
configure stylus properties as well as touch properties, but most of the
events that they send are TOOL_TYPE_FINGER. Previously, this triggered a
crash in PreferStylusOverTouchBlocker.

Bug: 222531989
Test: atest inputflinger_tests
Change-Id: Ifbb08858a4dfebc95c30ca19d6e68533855db7e4