Revert "TouchInputMapper: remove PointerUsage code"

This reverts commit 0917213c.

Reason for revert: it causes small changes in the input event stream for
drawing tablets and absolute mice, which don't affect compatibility but
cause failures when the cleaned-up TouchInputMapper is tested against
the old CTS tests.

Reverted changes: /q/submissionid:33669427-remove-touchpad-stack-flag

Bug: 420320431
Test: $ atest CtsInputTestCases
Flag: com.android.input.flags.disable_touch_input_mapper_pointer_usage
(cherry picked from https://googleplex-android-review.googlesource.com/q/commit:0814e813f1125373e20233ba0e5259733bd50396)
Merged-In: I5d3ec0b75da78e89a50cd1a0e9623b3b495f177a
Change-Id: I5d3ec0b75da78e89a50cd1a0e9623b3b495f177a