Block touches when stylus is down

Since we haven't yet added simultaneous touch and stylus support, let's
improve the user experience by blocking all touch when the stylus is
down.

Bug: 210159205
Test: atest inputflinger_tests
Change-Id: Id6a6467d7feb7c7d91770ddbd63b92583832d504
(cherry picked from commit a3c8e51901d17f696838d3e8260464f7437468a5)
7 files changed