selftests: txtimestamp: add SCM_TS_OPT_ID test

Extend txtimestamp test to run with fixed tskey using
SCM_TS_OPT_ID control message for all types of sockets.

Reviewed-by: Jason Xing <kerneljasonxing@gmail.com>
Reviewed-by: Willem de Bruijn <willemb@google.com>
Signed-off-by: Vadim Fedorenko <vadfed@meta.com>
Link: https://patch.msgid.link/20241001125716.2832769-4-vadfed@meta.com


Signed-off-by: Jakub Kicinski <kuba@kernel.org>