Merge branch 'selftests-net-add-packetdrill'

Willem de Bruijn says:

====================
selftests/net: add packetdrill

Lay the groundwork to import into kselftests the over 150 packetdrill
TCP/IP conformance tests on github.com/google/packetdrill.

1/2: add kselftest infra for TEST_PROGS that need an interpreter

2/2: add the specific packetdrill tests
====================

Link: https://patch.msgid.link/20240905231653.2427327-1-willemdebruijn.kernel@gmail.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>