Handle pointer location setting in InputSettingsObserver

We got a report that the pointer location developer option is not
being properly set per user; testing it confirmed that show
touches worked as expected while pointer location did not. After
investigating, the pointer location setting was being applied in
`WindowManagerService`, which generally deals with global settings,
while all the input settings are handled in `InputSettingsObserver`.

This CL moves the handling of the pointer location setting to
`InputSettingsObserver`, which seems more natural.

Test: confirmed that pointer location is now properly set on all users
Bug: 288023565
Change-Id: Ic2ecd890bd32e60a2fae4d5d40d4ff8f785ee3cc