Implement explicit storing of the server_finished_hash

Implement explicit storing of the server_finished_hash

tls13_change_cipher_state was storing the server_finished_hash as a
side effect of its operation. This decision is better made by the state
machine which actually knows what state we are in.

Reviewed-by: Neil Horman <nhorman@openssl.org>
Reviewed-by: Tomas Mraz <tomas@openssl.org>
(Merged from https://github.com/openssl/openssl/pull/27732)