Fix moves/forward

Clang has new checks for std::move/std::forward correctness, which
catches quite a few "wrong" things where we were making copies of
callback handlers.

Unfortunately, the lambda syntax of

callback{std::forward<Callback>(callback)}

in a capture confuses it, so change usages to
callback = std::forward<Callback>(callback)

to be consistent.

Tested: Redfish service validator passes.

Change-Id: I7a111ec00cf78ecb7d5f5b102c786c1c14d74384
Signed-off-by: Ed Tanous <ed@tanous.net>
diff --git a/http/app.hpp b/http/app.hpp
index 1a7af83..eeb331e 100644
--- a/http/app.hpp
+++ b/http/app.hpp
@@ -63,7 +63,7 @@
         router.handle(req, asyncResp);
     }
 
-    DynamicRule& routeDynamic(std::string&& rule)
+    DynamicRule& routeDynamic(const std::string& rule)
     {
         return router.newRuleDynamic(rule);
     }