PointerChoreographer: Add drawing tablet support

PointerChoreographer does not yet support drawing tablets. Add support
by creating a MousePointerController for each drawing tablet that is
connected. Use a MousePointerController so that the default icon is the
same as for a mouse (arrow) instead of for a stylus (no icon).

The icon will only show while the stylus is hovering or touching.

Bug: 329849066
Test: atest inputflinger_tests
Change-Id: I0cbb4a8efc8fd5e50ddfdad2b60df0195a3dce16