Introduce SSL_CTX_new_with_libex()

Introduce SSL_CTX_new_with_libex()

We add the ability to specify an OPENSSL_CTX (which may be NULL for the
default context) and a property query string for use during algorithm
fetch operations.

For example, in this way one SSL_CTX could be used the default provider,
and another one could be used with the FIPS provider.

At this stage we don't use these values. That will come later.

Reviewed-by: Richard Levitte <levitte@openssl.org>
Reviewed-by: Paul Dale <paul.dale@oracle.com>
(Merged from https://github.com/openssl/openssl/pull/10866)