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.cc b/quic/test_tools/quic_test_utils.cc
index 5021068..38873dd 100644
--- a/quic/test_tools/quic_test_utils.cc
+++ b/quic/test_tools/quic_test_utils.cc
@@ -1169,6 +1169,14 @@
          QuicUtils::StreamIdDelta(version) * n;
 }
 
+QuicStreamId GetNthClientInitiatedUnidirectionalStreamId(
+    QuicTransportVersion version,
+    int n) {
+  return QuicUtils::GetFirstUnidirectionalStreamId(version,
+                                                   Perspective::IS_CLIENT) +
+         QuicUtils::StreamIdDelta(version) * n;
+}
+
 StreamType DetermineStreamType(QuicStreamId id,
                                QuicTransportVersion version,
                                Perspective perspective,