REORG: include: move arg.h to haproxy/arg{,-t}.h

Almost no change was needed; chunk.h was replaced with buf-t.h.
It dpeends on types/vars.h and types/protocol_buffers.h.
diff --git a/src/map.c b/src/map.c
index 8dc1b51..df24ed2 100644
--- a/src/map.c
+++ b/src/map.c
@@ -24,7 +24,7 @@
 #include <types/stats.h>
 
 #include <proto/applet.h>
-#include <proto/arg.h>
+#include <haproxy/arg.h>
 #include <proto/cli.h>
 #include <proto/log.h>
 #include <proto/map.h>