Test framework output improvement.

Format the test failure output more nicely.

More vertical space is used to make things a little clearer.  Tests are expected
to pass so this doesn't impact the normal case.

Strings and memory comparisons highlight differences.

Reviewed-by: Rich Salz <rsalz@openssl.org>
Reviewed-by: Richard Levitte <levitte@openssl.org>
(Merged from https://github.com/openssl/openssl/pull/3357)