TUN-7227: Migrate to devincarr/quic-go

The lucas-clemente/quic-go package moved namespaces and our branch
went stale, this new fork provides support for the new quic-go repo
and applies the max datagram frame size change.

Until the max datagram frame size support gets upstreamed into quic-go,
this can be used to unblock go 1.20 support as the old
lucas-clemente/quic-go will not get go 1.20 support.

vendor/github.com/quic-go/quic-go/sys_conn_df.go

@@ -0,0 +1,15 @@
+//go:build !linux && !windows
+
+package quic
+
+import "syscall"
+
+func setDF(rawConn syscall.RawConn) error {
+	// no-op on unsupported platforms
+	return nil
+}
+
+func isMsgSizeErr(err error) bool {
+	// to be implemented for more specific platforms
+	return false
+}