tests: net: socket_tls: test different TLS configurations with sockets

This commit adds a test to showcase how to configure TLS 1.2 and 1.3
socket connections against an OpenSSL server. Only a limited number
of combinations are available for now:

- TLS 1.2
	- RSA certificate and key exchange.
	- ECDSA certificate and ECDHE key exchange.

- TLS 1.3 only supports ephemeral (ECDHE) key exchange with/without
  session tickets.

Since the goal is to test TLS connection and not low level ethernet
functionalities or similar, the only supported platform is "native_sim"
where Linux sockets are used to connect to the OpenSSL server locally.

The idea is that the Zephyr application acts a client and tries to connect
to the OpenSSL server running on the same PC. For sake of simplificity a
bash script is provided to start the OpenSSL server properly.
For completeness a bash script is also provided to re-generate
certificates and keys.

Signed-off-by: Valerio Setti <vsetti@baylibre.com>