Add expireIn implementation to LocationRequest

Clients should no longer need to reset expireIn every time they make a
location request. Also allow clients of getCurrentLocation() to set
their own timeout if desired, and enforce a timeout for
requestSingleUpdate().

Bug: 133356925
Bug: 142956404
Test: atest LocationManagerTest
Change-Id: I1b3a4d8d6ef249a2395b0d30bf7b92a8d4cfe933