Ignore the record version for early alerts

Ignore the record version for early alerts

On receiving the first flight from the peer, we do not yet know if
we are using TLSv1.3. In particular, we might get an alert record
with record version 0x0300 from a pre-TLSv1.2 peer in response to
our client hello. Ignore the record version instead of sending a
protocol version alert in that situtation. This may also be hit
when talking to a LibreSSL 3.3 server with an illegal SNI.

Part of an issue reported by danj.

ok jsing