[ipsec-qtaguid] Reserve mark, add ipsec bw exemptions

This change reserves a mark denoting that a packet has already been
accounted for, along with adding rules in BandwidthController to support
IPSec packets being billed correctly.

Bug: 62994731
Test: BandwidthControllerTest updated, passing. CTS tests also modified
and passing

Change-Id: I8b42975d1502a0d3b9e533bddc0892cfe1556bed
6 files changed