MINOR: quic: Make QUIC-TLS support at least two initial salts

MINOR: quic: Make QUIC-TLS support at least two initial salts

These salts are used to derive initial secrets to decrypt the first Initial packet.
We support draft-29 and v1 QUIC version initial salts.
Add parameters to our QUIC-TLS API functions used to derive these secret for
these salts.
Make our xprt_quic use the correct initial salt upon QUIC version field found in
the first paquet. Useful to support connections with curl which use draft-29
QUIC version.