http3: hide SendDatagram and ReceiveDatagram on the Connection (#4427)

HTTP datagrams are bound to streams. It shouldn't be possible to send
datagrams on the http3.Connection.

http3/conn.go

@@ -2,6 +2,7 @@ package http3
 
 import (
  "context"
+ "net"
  "sync/atomic"
 
  "github.com/quic-go/quic-go"
@@ -11,7 +12,19 @@ import (
 )
 
 type Connection interface {
- quic.Connection
+ // all methods from the quic.Connection expect for SendDatagram and ReceiveDatagram
+ AcceptStream(context.Context) (quic.Stream, error)
+ AcceptUniStream(context.Context) (quic.ReceiveStream, error)
+ OpenStream() (quic.Stream, error)
+ OpenStreamSync(context.Context) (quic.Stream, error)
+ OpenUniStream() (quic.SendStream, error)
+ OpenUniStreamSync(context.Context) (quic.SendStream, error)
+ LocalAddr() net.Addr
+ RemoteAddr() net.Addr
+ CloseWithError(quic.ApplicationErrorCode, string) error
+ Context() context.Context
+ ConnectionState() quic.ConnectionState
+
  // ReceivedSettings returns a channel that is closed once the client's SETTINGS frame was received.
  ReceivedSettings() <-chan struct{}
  // Settings returns the settings received on this connection.