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

This one is particularly difficult to split because it provides all the
functions used to manipulate a proxy state and to retrieve names or IDs
for error reporting, and as such, it was included in 73 files (down to
68 after cleanup). It would deserve a small cleanup though the cut points
are not obvious at the moment given the number of structs involved in
the struct proxy itself.
diff --git a/src/cache.c b/src/cache.c
index 0858a8d..e95493a 100644
--- a/src/cache.c
+++ b/src/cache.c
@@ -19,14 +19,12 @@
 #include <haproxy/http_htx.h>
 #include <haproxy/http_rules.h>
 #include <haproxy/log.h>
+#include <haproxy/proxy.h>
 #include <haproxy/shctx.h>
 #include <haproxy/stream_interface.h>
 #include <import/eb32tree.h>
 #include <import/sha1.h>
 
-#include <types/proxy.h>
-
-#include <proto/proxy.h>
 #include <proto/stream.h>