sslapitest: add test ktls Rx

Add a unit-test for ktls receive side.

Change-Id: I890588681d05fba419f644f6d903be6dc83c9ed5
Signed-off-by: Boris Pismenny <borisp@mellanox.com>

Reviewed-by: Bernd Edlinger <bernd.edlinger@hotmail.de>
Reviewed-by: Matt Caswell <matt@openssl.org>
(Merged from https://github.com/openssl/openssl/pull/7848)