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

The type file was slightly tidied. The cli-specific APPCTX_CLI_ST1_* flag
definitions were moved to cli.h. The type file was adjusted to include
buf-t.h and not the huge buf.h. A few call places were fixed because they
did not need this include.
diff --git a/include/proto/proxy.h b/include/proto/proxy.h
index 6a9aa55..f5f0bf3 100644
--- a/include/proto/proxy.h
+++ b/include/proto/proxy.h
@@ -22,11 +22,11 @@
 #ifndef _PROTO_PROXY_H
 #define _PROTO_PROXY_H
 
+#include <haproxy/applet-t.h>
 #include <haproxy/api.h>
 #include <haproxy/listener-t.h>
 #include <haproxy/ticks.h>
 #include <haproxy/time.h>
-#include <types/applet.h>
 #include <haproxy/global-t.h>
 #include <types/proxy.h>
 #include <haproxy/freq_ctr.h>