Add support for HTTP/3 control stream.

Upon initialization, QuicSpdySession will create a write_unidirectional stream
and write stream type and settings when crypto handshake is completed.

The peer will receive the stream type and create a read_unidirectional stream
that reads the settings.

gfe-relnote: version 99 only. Not in prod.
PiperOrigin-RevId: 252650934
Change-Id: I708280eb94dea3d6eb7e54b96ce8ee91e2b8684f
diff --git a/quic/test_tools/quic_test_utils.h b/quic/test_tools/quic_test_utils.h
index 8f1cb7a..cb51a3b 100644
--- a/quic/test_tools/quic_test_utils.h
+++ b/quic/test_tools/quic_test_utils.h
@@ -1170,6 +1170,9 @@
 QuicStreamId GetNthServerInitiatedUnidirectionalStreamId(
     QuicTransportVersion version,
     int n);
+QuicStreamId GetNthClientInitiatedUnidirectionalStreamId(
+    QuicTransportVersion version,
+    int n);
 
 StreamType DetermineStreamType(QuicStreamId id,
                                QuicTransportVersion version,