sslapitest: add test ktls

Add a unit-test for ktls.

Signed-off-by: Boris Pismenny <borisp@mellanox.com>

Reviewed-by: Tim Hudson <tjh@openssl.org>
Reviewed-by: Paul Yang <yang.yang@baishancloud.com>
Reviewed-by: Matt Caswell <matt@openssl.org>
(Merged from https://github.com/openssl/openssl/pull/5253)