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/utils.cpp b/src/utils.cpp
index b5bac09..db476f3 100644
--- a/src/utils.cpp
+++ b/src/utils.cpp
@@ -3,7 +3,6 @@
 
 #include "utils.hpp"
 
-#include <boost/container/flat_map.hpp>
 #include <boost/lexical_cast.hpp>
 #include <phosphor-logging/lg2.hpp>
 #include <sdbusplus/bus/match.hpp>
@@ -11,6 +10,7 @@
 #include <algorithm>
 #include <cctype>
 #include <filesystem>
+#include <flat_map>
 #include <map>
 #include <ranges>
 #include <regex>
@@ -79,7 +79,7 @@
 }
 
 bool getI2cDevicePaths(const fs::path& dirPath,
-                       boost::container::flat_map<size_t, fs::path>& busPaths)
+                       std::flat_map<size_t, fs::path>& busPaths)
 {
     if (!fs::exists(dirPath))
     {