Migrate telephony code away from Time

Switch telephony code under frameworks/base/ away from
android.text.format.Time. Time uses 32-bit ints to represent
seconds from the start of the Unix epoch and therefore will
break in 2038. Moving to java.time types avoids this problem.

Bug: 16550209
Test: build / boot / treehugger
Change-Id: I49e748f686709c0c38aa5ba37b37ec4ed1e68b55