… chains

This change makes the wolfSSL backend sent the complete TLS client certificate
chain. This align the wolfSSL backend with the behavior of the mbedTLS backend.
Some servers need the intermediate certificates to verify a client certificate.
If the provided PEM file contains only a single certificate this change has no effect
and the behavior will be as before.
This impacts higher level APIs to function as someone would expect.
E.g.: esp_websocket_client_config_t.client_cert: when passing here a pem
file containing 2 certificates (the CA's and the client's) it would be
expected that both are transmitted during TLS handshake.

Almost all sites these days are virtually hosted and hence
SNI (server name indicator TLS extension) should be enabled by
default.

In addition this change enables OCSP (online server status protocol)
support for esp-tls clients using the wolfSSL backend.
The 3 code lines enable OCSP stabling v1.
By default this feature is disabled.
(I will send another PR on esp-wolfssl repository to allow to
enable it easily.)