Ensure that the certificate required alert actually gets sent (and doesn't
get translated into handshake failure in TLSv1.3).

Ensure that proper reason codes are given for the new TLSv1.3 alerts.

Remove an out of date macro for TLS13_AD_END_OF_EARLY_DATA. This is a left
over from an earlier TLSv1.3 draft that is no longer used.

Fixes #6804
Reviewed-by: NTim Hudson <tjh@openssl.org>
(Merged from https://github.com/openssl/openssl/pull/6809)