item_updater: sort ubi specific code

Add item_updater_helper and implement it in ubi and static layouts.

Tested: Build this repo on both Romulus and Witherspoon OK;
        Tested on Romulus and Witherspoon that code update works fine.

Change-Id: I706cfe63900f89bb41672dcc745b3483e06838c7
Signed-off-by: Lei YU <mine260309@gmail.com>
diff --git a/item_updater.hpp b/item_updater.hpp
index 9fda860..330ec82 100644
--- a/item_updater.hpp
+++ b/item_updater.hpp
@@ -2,6 +2,7 @@
 
 #include <sdbusplus/server.hpp>
 #include "activation.hpp"
+#include "item_updater_helper.hpp"
 #include "version.hpp"
 #include <xyz/openbmc_project/Common/FactoryReset/server.hpp>
 #include <xyz/openbmc_project/Control/FieldMode/server.hpp>
@@ -47,7 +48,7 @@
      * @param[in] bus    - The D-Bus bus object
      */
     ItemUpdater(sdbusplus::bus::bus& bus, const std::string& path) :
-        ItemUpdaterInherit(bus, path.c_str(), false), bus(bus),
+        ItemUpdaterInherit(bus, path.c_str(), false), bus(bus), helper(bus),
         versionMatch(bus,
                      MatchRules::interfacesAdded() +
                          MatchRules::path("/xyz/openbmc_project/software"),
@@ -188,6 +189,9 @@
     /** @brief Persistent sdbusplus D-Bus bus connection. */
     sdbusplus::bus::bus& bus;
 
+    /** @brief The helper of image updater. */
+    Helper helper;
+
     /** @brief Persistent map of Activation D-Bus objects and their
      * version id */
     std::map<std::string, std::unique_ptr<Activation>> activations;