(touch-mode-md 2/n) Add md touch mode support in InputDispatcher

Major changes in this CL:
* Drop kPerDisplayTouchModeEnabled (keep the native layer simple);
* Include display id in TouchModeEntry;
* Cache touch mode state per display id.

Bug: 198499018
Test: atest inputflinger_tests
Change-Id: Idc800e08bfca1c19342ad34865bd6c9e5dc6a7d3