Merge branch 'selftests-bpf-migrate-test_tunnel-sh-to-test_progs'

Bastien Curutchet says:

====================
selftests/bpf: Migrate test_tunnel.sh to test_progs

Hi all,

This patch series continues the work to migrate the *.sh tests into
prog_tests framework.

The test_tunnel.sh script has already been partly migrated to
test_progs in prog_tests/test_tunnel.c so I add my work to it.

PATCH 1 & 2 create some helpers to avoid code duplication and ease the
migration in the following patches.
PATCH 3 to 9 migrate the tests of gre, ip6gre, erspan, ip6erspan,
geneve, ip6geneve and ip6tnl tunnels.
PATCH 10 removes test_tunnel.sh
====================

Link: https://patch.msgid.link/20250303-tunnels-v2-0-8329f38f0678@bootlin.com
Signed-off-by: Martin KaFai Lau <martin.lau@kernel.org>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>