s_client, s_server: do generic SSL configuration first, specialization after

We did the SSL_CONF_cmd() pass last of all things that could affect
the SSL ctx.  However, the results of this, for example:

    -max_protocol TLSv1.3 -tls1_2

... would mean that the protocol min got set to TLSv1.2 and the
protocol max to TLSv1.3, when they should clearly both be TLSv1.2.

However, if we see the SSL_CONF_cmd() switches as generic and those
internal to s_client and s_server as specialisations, we get something
that makes a little more sense.

Reviewed-by: Tim Hudson <tjh@openssl.org>
Reviewed-by: Matt Caswell <matt@openssl.org>
(Merged from https://github.com/openssl/openssl/pull/5679)