Add support for cipher aliases DHE, EDH and EECDH.

Add define SSL_CTRL_GET_CHAIN_CERTS to help hitch and other programs detect SSL_CTX_get0_chain_certs is supported.

Add wolfSSL_get_locking_callback.

Allow using ECDHE+RSA cipher suites when ECDHE alias is used while in OpenSSL compatibility mode.

Add more alerts for hitch.

SSL_CM should use the CTX's x509_store_pt if available.

Add support for SSL_CERT_FILE and SSL_CERT_DIR.  Load default OpenSSL TLS 1.3 ciphers when using OPENSSL_COMPATIBLE_DEFAULTS.

Use wolfSSL_sk_X509_new_null to allocate WOLFSSL_STACK in wolfSSL_CTX_get_extra_chain_certs.  Previous approach of malloc'ing without setting type/memsetting was leading to a segfault.

Add --enable-hitch.

hitch: Add unit tests for new APIs, fix a couple of issues uncovered by unit testing.

Correct behavior of wolfSSL_BIO_set_mem_buf for BIO_CLOSE/NOCLOSE and update unit test accordingly.

Add Github action test for hitch.