The new set of API replace the PacketKeepalive system API
which is only specific for IPsec NAT-T keepalive packet. Allows
applications to request different types of keepalives through
the same set of API.
By using keepalives, applications could request system to
periodically send specific packets on their behalf, using
hardware offload to save battery power.
This change would only address interface change and test part of
original functionality. After all reference of PacketKeepalive
are removed, another change would be submitted to remove old
API.
Bug: 114151147
Test: atest FrameworksNetTests
Change-Id: I3367666810acc44d5ad20e19acd4bf936e8b5d9c
a86defca11