Move location-related code into client library

These first-party only methods can only be called by privileged
packages, and Settings.Secure already applies strict permission check to
them. Therefore moving the code into client library can save us from
unnecessary binder calls, and can also make checking the caller package
name much easier.

Test: Manual
Change-Id: I76a939a660357f87b01ff4ac07ec3f17093d3c41