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/flt_trace.c b/src/flt_trace.c
index 01278bb..940ddd2 100644
--- a/src/flt_trace.c
+++ b/src/flt_trace.c
@@ -19,11 +19,11 @@
 #include <haproxy/http_htx.h>
 #include <haproxy/htx.h>
 #include <haproxy/log.h>
+#include <haproxy/proxy-t.h>
 #include <haproxy/tools.h>
 #include <haproxy/time.h>
 
 #include <haproxy/global.h>
-#include <types/proxy.h>
 #include <types/stream.h>
 
 #include <proto/stream.h>