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/ut/lock_test.cpp b/redfish-core/ut/lock_test.cpp
index e89377d..7ee2b71 100644
--- a/redfish-core/ut/lock_test.cpp
+++ b/redfish-core/ut/lock_test.cpp
@@ -100,7 +100,7 @@
         auto status = Lock::isItMyLock(tids, ids);
         return status;
     }
-    RcGetLockList getList(std::vector<std::string>& listSessionid)
+    RcGetLockList getList(const std::vector<std::string>& listSessionid)
     {
         auto status = Lock::getLockList(listSessionid);
         return status;