Fix const correctness issues

cppcheck correctly notes that a lot of variables in the new code can be
const.  Make most of them const.

Tested: WIP

Signed-off-by: Ed Tanous <edtanous@google.com>
Change-Id: I8f37b6353fd707923f533e1d61c5b5419282bf23
diff --git a/redfish-core/lib/account_service.hpp b/redfish-core/lib/account_service.hpp
index a773048..f8ba322 100644
--- a/redfish-core/lib/account_service.hpp
+++ b/redfish-core/lib/account_service.hpp
@@ -1328,7 +1328,7 @@
         "org.freedesktop.DBus.Properties", "GetAll",
         "xyz.openbmc_project.User.AccountPolicy");
 
-    auto callback = [asyncResp](bool success, LDAPConfigData& confData,
+    auto callback = [asyncResp](bool success, const LDAPConfigData& confData,
                                 const std::string& ldapType) {
         if (!success)
         {