Add util to add an ARP table entry

This is to be used by the new DhcpServer to add ARP entries with new
addresses before sending unicast responses.

Test: manual: cat /proc/net/arp with implementation based on this
Bug: b/109584964
Change-Id: I3559893583aa3c49b188ad689a41ee2f3e9d9bf3
2 files changed
tree: 32fd3b5fb784f84c66b7314a7a1b9c99b468010a
  1. core/
  2. services/
  3. tests/