tools: ynltool: create skeleton for the C command

tools: ynltool: create skeleton for the C command

Based on past discussions it seems like integration of YNL into
iproute2 is unlikely. YNL itself is not great as a C library,
since it has no backward compat (we routinely change types).

Most of the operations can be performed with the generic Python
CLI directly. There is, however, a handful of operations where
summarization of kernel output is very useful (mostly related
to stats: page-pool, qstat).

Create a command (inspired by bpftool, I think it stood the test
of time reasonably well) to be able to plug the subcommands into.

Link: https://lore.kernel.org/1754895902-8790-1-git-send-email-ernis@linux.microsoft.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
Link: https://patch.msgid.link/20251107162227.980672-2-kuba@kernel.org
Acked-by: Stanislav Fomichev <sdf@fomichev.me>
Signed-off-by: Paolo Abeni <pabeni@redhat.com>