Add support for SHA256/192

Add support for SHA256/192

This is defined in NIST SP 800-208 as the truncation to 192 bits of
SHA256. Unlike other truncated hashes in the SHA2 suite, this variant
doesn't have a different initial state, it is just a pure truncation
of the output.

Reviewed-by: Tomas Mraz <tomas@openssl.org>
Reviewed-by: Paul Dale <pauli@openssl.org>
(Merged from https://github.com/openssl/openssl/pull/21180)