REORG: stconn: rename conn_stream.{c,h} to stconn.{c,h}

There's no more reason for keepin the code and definitions in conn_stream,
let's move all that to stconn. The alphabetical ordering of include files
was adjusted.
diff --git a/src/cli.c b/src/cli.c
index 8bbe853..8f21b2e 100644
--- a/src/cli.c
+++ b/src/cli.c
@@ -34,7 +34,6 @@
 #include <haproxy/channel.h>
 #include <haproxy/check.h>
 #include <haproxy/cli.h>
-#include <haproxy/conn_stream.h>
 #include <haproxy/compression.h>
 #include <haproxy/dns-t.h>
 #include <haproxy/errors.h>
@@ -58,6 +57,7 @@
 #include <haproxy/session.h>
 #include <haproxy/sock.h>
 #include <haproxy/stats-t.h>
+#include <haproxy/stconn.h>
 #include <haproxy/stream.h>
 #include <haproxy/task.h>
 #include <haproxy/ticks.h>