Flat map all the things

In an earlier commit, entity-manager gained required dependency
on std::flat_map.  This means that EM can only compile with gcc-15,
which the project only recently moved to.  Rather than move backwards,
port forward all uses of boost flat_map and flat_set to their std
equivalents.

Tested: entity-manager launches and enumerates devices on
gb200-obmc.

Change-Id: Id24803057711c60d5b00f436db80b27edbb756a3
Signed-off-by: Ed Tanous <etanous@nvidia.com>
diff --git a/src/entity_manager/log_device_inventory.cpp b/src/entity_manager/log_device_inventory.cpp
index 9662c97..93cf156 100644
--- a/src/entity_manager/log_device_inventory.cpp
+++ b/src/entity_manager/log_device_inventory.cpp
@@ -2,10 +2,10 @@
 
 #include <systemd/sd-journal.h>
 
-#include <boost/container/flat_map.hpp>
 #include <nlohmann/json.hpp>
 #include <xyz/openbmc_project/Inventory/Decorator/Asset/common.hpp>
 
+#include <flat_map>
 #include <string>
 
 struct InvAddRemoveInfo