Introduce SSL_CIPHER_get_protocol_id

The returned ID matches with what IANA specifies (or goes on the
wire anyway, IANA notwithstanding).

Doc is added.

Reviewed-by: Matt Caswell <matt@openssl.org>
Reviewed-by: Ben Kaduk <kaduk@mit.edu>
(Merged from https://github.com/openssl/openssl/pull/4107)