Add a selftest that loads the kfunc in sleepable and non-sleepable
lsm/socket_connect programs and checks that a value set via fsetxattr()
on a socket is read back.
Link: https://patch.msgid.link/20260617-work-bpf-sock-xattr-v1-2-a1276f7c9da3@kernel.org
Reviewed-by: John Fastabend <john.fastabend@gmail.com>
Signed-off-by: Christian Brauner (Amutable) <brauner@kernel.org>