If a ticket key callback returns 0 in TLSv1.3 don't send a ticket
If we can't construct the ticket don't send one. This requires a change
to the TLS state machine to be able to a handle a construction function
deciding not to send a message after all.
Fixes #18977
Reviewed-by: Viktor Dukhovni <viktor@openssl.org> Reviewed-by: Tomas Mraz <tomas@openssl.org> Reviewed-by: Hugo Landau <hlandau@openssl.org>
(Merged from https://github.com/openssl/openssl/pull/18990)