fw_update: Introduce AggregateUpdateManager

Description:
This commit introduces the `AggregateUpdateManager` class for handling
multiple firmware update sessions simultaneously. The
`AggregateUpdateManager` acts as a reverse proxy for PLDM messages,
routing them to the appropriate `UpdateManager` instance based on the
`instanceId`. This allows for concurrent firmware updates, improving
the efficiency and flexibility of the firmware update process.

Motivation:
We have introduced the `FirmwareInventory`/`FirmwareInventoryManager`
classes to manage D-Bus interfaces for firmware update, After that, we
would like to implement the `StartUpdate` method for `FirmwareInventory`
properly for the update process implementation[1], which
`AggregateUpdateManager` will help route the command to the specific
update sessions.

Details of the PLDM message reverse proxy:
By the implementation, different update session would be handled with
different `instanceId`s, which can help `UpdateManager`s to identify
whether the message is for them or not.
Whenever a PLDM response message is received, the flow that
the `AggregateUpdateManager` do:
 1. Handle the message for existing update flow if the instance_id
    (the pldm instance numbers) matches the update task which using the
    existing update flow.
 2. Traverse forward the message to each `ItemUpdateManager`
    (implementation in the next patch) instances if there's no match in
    step 1.
 3. Return error message PLDM_FWUP_COMMAND_NOT_EXPECTED if no matches in
    step 2.

[1]: https://gerrit.openbmc.org/c/openbmc/pldm/+/74774

Change-Id: Icfdb8d238121f9f44a624396e00b378e491ce652
Signed-off-by: Unive Tien <unive.tien.wiwynn@gmail.com>
diff --git a/fw-update/firmware_inventory_manager.hpp b/fw-update/firmware_inventory_manager.hpp
index e6616ce..45ffd8e 100644
--- a/fw-update/firmware_inventory_manager.hpp
+++ b/fw-update/firmware_inventory_manager.hpp
@@ -1,5 +1,6 @@
 #pragma once
 
+#include "aggregate_update_manager.hpp"
 #include "common/types.hpp"
 #include "firmware_inventory.hpp"
 
@@ -40,8 +41,9 @@
      */
     explicit FirmwareInventoryManager(
         const pldm::utils::DBusHandler* dbusHandler,
-        const Configurations& config) :
-        dbusHandler(dbusHandler), configurations(config)
+        const Configurations& config, AggregateUpdateManager& updateManager) :
+        dbusHandler(dbusHandler), configurations(config),
+        updateManager(updateManager)
     {}
 
     /**
@@ -96,6 +98,11 @@
      *        the initialization of the FirmwareInventoryManager.
      */
     const Configurations& configurations;
+
+    /**
+     * @brief Reference to the aggregate update manager
+     */
+    AggregateUpdateManager& updateManager;
 };
 
 } // namespace pldm::fw_update