Augment ossl_quic_wire_decode_pkt_hdr

Augment ossl_quic_wire_decode_pkt_hdr

In preparation for supporting the handling of version negotiation, we
need to be able to detect why the decoding of quic header failed.
Specifically, ossl_quic_wire_decode_pkt_hdr fails if the version
provided in the header isn't QUIC_VERSION_1.  We want to keep that, as
we don't support anything else, but the server code needs to
differentiate when we fail decode because of a version problem, vs some
other more fatal malforming issue.

So add a uint64_t *fail_cause pointer that gets filled out with a
failure cause.  We only use VERSION failures right now, but we can
expand this later if needed

Reviewed-by: Tomas Mraz <tomas@openssl.org>
Reviewed-by: Saša Nedvědický <sashan@openssl.org>
(Merged from https://github.com/openssl/openssl/pull/25968)