REORG: include: move http_fetch.h to haproxy/http_fetch.h

There's no type file for this trivial one. The unneeded dependency on
htx.h was dropped.
diff --git a/src/51d.c b/src/51d.c
index 529a8ba..3bdc5bf 100644
--- a/src/51d.c
+++ b/src/51d.c
@@ -5,11 +5,11 @@
 #include <haproxy/chunk.h>
 #include <haproxy/buf-t.h>
 #include <haproxy/errors.h>
+#include <haproxy/http_fetch.h>
 #include <haproxy/http_htx.h>
 #include <haproxy/thread.h>
 #include <haproxy/global.h>
 #include <haproxy/arg.h>
-#include <proto/http_fetch.h>
 #include <proto/log.h>
 #include <proto/http_ana.h>
 #include <haproxy/sample.h>