Support QUIC Client connection IDs

This CL is almost exclusively plumbing client connection IDs through the stack now that previous CLs handled the behavior changes. It also adds tests for the new behavior at each layer.

gfe-relnote: support client connection IDs, protected by quic_do_not_override_connection_id
PiperOrigin-RevId: 251599233
Change-Id: I7cda028f8aa56e6da451b6d86877fd0f84d93531
diff --git a/quic/test_tools/quic_framer_peer.cc b/quic/test_tools/quic_framer_peer.cc
index 94493c3..eea4fd6 100644
--- a/quic/test_tools/quic_framer_peer.cc
+++ b/quic/test_tools/quic_framer_peer.cc
@@ -29,6 +29,13 @@
 }
 
 // static
+void QuicFramerPeer::SetLastSerializedClientConnectionId(
+    QuicFramer* framer,
+    QuicConnectionId client_connection_id) {
+  framer->last_serialized_client_connection_id_ = client_connection_id;
+}
+
+// static
 void QuicFramerPeer::SetLargestPacketNumber(QuicFramer* framer,
                                             QuicPacketNumber packet_number) {
   framer->largest_packet_number_ = packet_number;