Pull out NITZ-related logic into a separate class

This commit extracts several hundred lines of NITZ-related
logic from ServiceStateTracker into a separate class. No
behavior changes are intended: this is a pure refactoring
to move the logic into a separate, (ultimately) more
testable form. This is the first commit of several.

Bug: 63743683
Test: Build / Boot
(cherry picked from commit 10bdf3dd)
Merged-In: Ic19ce01167892d7cfbd03d34fea37181bb43cc7c
Change-Id: Ic19ce01167892d7cfbd03d34fea37181bb43cc7c