selftests/net: Add TCP_REPAIR TCP-AO tests

The test plan is:
1. check that TCP-AO connection may be restored on another socket
2. check restore with wrong send/recv ISN (checking that they are
part of MAC generation)
3. check restore with wrong SEQ number extension (checking that
high bytes of it taken into MAC generation)

Sample output expected:
> # ./restore_ipv4
> 1..20
> # 1412[lib/setup.c:254] rand seed 1686610825
> TAP version 13
> ok 1 TCP-AO migrate to another socket: server alive
> ok 2 TCP-AO migrate to another socket: post-migrate connection is alive
> ok 3 TCP-AO migrate to another socket: counter TCPAOGood increased 23 => 44
> ok 4 TCP-AO migrate to another socket: counter TCPAOGood increased 22 => 42
> ok 5 TCP-AO with wrong send ISN: server couldn't serve
> ok 6 TCP-AO with wrong send ISN: post-migrate connection is broken
> ok 7 TCP-AO with wrong send ISN: counter TCPAOBad increased 0 => 4
> ok 8 TCP-AO with wrong send ISN: counter TCPAOBad increased 0 => 3
> ok 9 TCP-AO with wrong receive ISN: server couldn't serve
> ok 10 TCP-AO with wrong receive ISN: post-migrate connection is broken
> ok 11 TCP-AO with wrong receive ISN: counter TCPAOBad increased 4 => 8
> ok 12 TCP-AO with wrong receive ISN: counter TCPAOBad increased 5 => 10
> ok 13 TCP-AO with wrong send SEQ ext number: server couldn't serve
> ok 14 TCP-AO with wrong send SEQ ext number: post-migrate connection is broken
> ok 15 TCP-AO with wrong send SEQ ext number: counter TCPAOBad increased 9 => 10
> ok 16 TCP-AO with wrong send SEQ ext number: counter TCPAOBad increased 11 => 19
> ok 17 TCP-AO with wrong receive SEQ ext number: post-migrate connection is broken
> ok 18 TCP-AO with wrong receive SEQ ext number: server couldn't serve
> ok 19 TCP-AO with wrong receive SEQ ext number: counter TCPAOBad increased 10 => 18
> ok 20 TCP-AO with wrong receive SEQ ext number: counter TCPAOBad increased 20 => 23
> # Totals: pass:20 fail:0 xfail:0 xpass:0 skip:0 error:0

Signed-off-by: Dmitry Safonov <dima@arista.com>
Signed-off-by: David S. Miller <davem@davemloft.net>