Add a test for setting initial SNI in CH but not using it with early_data

Test for the bug where early_data is not accepted by the server when it
does not have an SNI callback set up, but the client sent a servername in
the initial ClientHello establishing the session.

Reviewed-by: Rich Salz <rsalz@openssl.org>
Reviewed-by: Ben Kaduk <kaduk@mit.edu>
(Merged from https://github.com/openssl/openssl/pull/4519)
