InputDispatcher: Use floats to represent location coordinates

This is an adapted backport of a downstream CL.

There should be no behavior changes in this CL.

Bug: 257118693
Test: atest inputflinger_tests
Change-Id: Ib877610197a641e9c179e0809ed962ae206ea6e5
Merged-In: Ib877610197a641e9c179e0809ed962ae206ea6e5