MINOR: quic: Add structures to maintain key phase information

MINOR: quic: Add structures to maintain key phase information

When running Key Update process, we must maintain much information
especially when the key phase bit has been toggled by the peer as
it is possible that it is due to late packets. This patch adds
quic_tls_kp new structure to do so. They are used to store
previous and next secrets, keys and IVs associated to the previous
and next RX key phase. We also need the next TX key phase information
to be able to encrypt packets for the next key phase.