Exempt Dialer from power restrictions temporarily after missing a call

For default dialers that manage missed call notifications themselves, they
may need to do multiple things after a missed call, including update the
call log.

In order for Dialer to not need to start a foreground service, Telecom will
exempt them from power restrictions for a default of 30 seconds after a
call is missed to remove the possiblity of causing an ANR.

Bug: 160724034
Test: atest TelecomUnitTests; check `adb shell cmd deviceidle tempwhitelist`
      after a missed call.
Change-Id: Id19a8563aef0b9f1888b3575e9daf7085d781e13