Dropping NAT-T keepalive packet from APF

Add NAT Traversal keepalive filter to APF program to
drop NAT-T keepalive packets when NAT-T keepalive
offload is starting.

Bug: 33530442
Test: - atest NetworkStackTests
      - atest FrameworksNetTests

Change-Id: If62ba7fdb5f0f0f0a7a59ec169e82b4e3147eedd
Merged-In: If62ba7fdb5f0f0f0a7a59ec169e82b4e3147eedd
Merged-In: Ib3416ec37f0de12daf882068e00673ad60438c1a
(cherry picked from commit 95538d2d)