Move OEM specific code to respective class

The requirement of re-collecting FRUs at host state change is OEM
specific and should be hosted by respective OEM class.
Supporting APIs moved from manager class so that it can be used by OEM
class.

Change-Id: If0f218de89635158dda068a0a4951c29a5710cbb
Signed-off-by: Sunny Srivastava <sunnsr25@in.ibm.com>
diff --git a/vpd-manager/oem-handler/ibm_handler.hpp b/vpd-manager/oem-handler/ibm_handler.hpp
index 35b905e..5bf6d65 100644
--- a/vpd-manager/oem-handler/ibm_handler.hpp
+++ b/vpd-manager/oem-handler/ibm_handler.hpp
@@ -45,6 +45,18 @@
 
   private:
     /**
+     * @brief API to register callback for Host state change.
+     */
+    void registerHostStateChangeCallback();
+
+    /**
+     * @brief API to process host state change callback.
+     *
+     * @param[in] i_msg - Callback message.
+     */
+    void hostStateChangeCallBack(sdbusplus::message_t& i_msg);
+
+    /**
      * @brief API to set timer to detect system VPD over D-Bus.
      *
      * System VPD is required before bus name for VPD-Manager is claimed. Once