Add IPv6 Handling for DSCP Policies and Support Interfaces with MAC Addresses

Add bpf functionality to handle IPv6 packets and apply
DSCP value.
Also support DSCP policy rules on multiple interfaces
simultaneously.

Test: atest DscpPolicyTest

Bug: 217166486
Change-Id: I452a87355fd0382a4c38b84aa3465505951d9bf0
6 files changed