Merge branch 'selftests-bpf-tc_links-tc_opts-unserialize-tests'

Bastien Curutchet says:

====================
Both tc_links.c and tc_opts.c do their tests on the loopback interface.
It prevents from parallelizing their executions.

Add a new behaviour to the test_progs framework that creates and opens a
new network namespace to run a test in it. This is done automatically on
tests whose names start with 'ns_'.

One test already has a name starting with 'ns_', so PATCH 1 renames it
to avoid conflicts. PATCH 2 introduces the test_progs 'feature'.
PATCH 3 & 4 convert some tests to use these dedicated namespaces.

Signed-off-by: Bastien Curutchet (eBPF Foundation) <bastien.curutchet@bootlin.com>
Changes in v2:
 - Handle the netns creation / opening directly in test_progs
 - Link to v1: https://lore.kernel.org/bpf/e3838d93-04e3-4e96-af53-e9e63550d7ba@bootlin.com
====================

Acked-by: Stanislav Fomichev <sdf@fomichev.me>
Link: https://patch.msgid.link/20250219-b4-tc_links-v2-0-14504db136b7@bootlin.com
Signed-off-by: Alexei Starovoitov <ast@kernel.org>