REORG: proto_htx: Move HTX analyzers & co to http_ana.{c,h} files

The old module proto_http does not exist anymore. All code dedicated to the HTTP
analysis is now grouped in the file proto_htx.c. So, to finish the polishing
after removing the legacy HTTP code, proto_htx.{c,h} files have been moved in
http_ana.{c,h} files.

In addition, all HTX analyzers and related functions prefixed with "htx_" have
been renamed to start with "http_" instead.
diff --git a/src/http_rules.c b/src/http_rules.c
index 5089200..b790c5f 100644
--- a/src/http_rules.c
+++ b/src/http_rules.c
@@ -33,7 +33,7 @@
 #include <proto/action.h>
 #include <proto/arg.h>
 #include <proto/http_rules.h>
-#include <proto/proto_http.h>
+#include <proto/http_ana.h>
 #include <proto/sample.h>