rename headers to match style

Moving headers from ".h" to ".hpp"

Reworked the header inclusion a bit so that host-ipmid is treated as a
library, and local headers aren't.

renamed apphandler.h => apphandler.hpp
renamed chassishandler.h => chassishandler.hpp
renamed globalhandler.h => globalhandler.hpp
renamed sensorhandler.h => sensorhandler.hpp
renamed storageaddsel.h => storageaddsel.hpp
renamed storagehandler.h => storagehandler.hpp
renamed systemintfcmds.h => systemintfcmds.hpp

Change-Id: I9d4ce3dd57e2e996800f9020a10cc10cdf2c3914
Signed-off-by: Patrick Venture <venture@google.com>
diff --git a/selutility.cpp b/selutility.cpp
index 8e04ad4..228bf62 100644
--- a/selutility.cpp
+++ b/selutility.cpp
@@ -1,5 +1,10 @@
+#include "config.h"
+
+#include "selutility.hpp"
+
 #include <chrono>
 #include <vector>
+
 #if __has_include(<filesystem>)
 #include <filesystem>
 #elif __has_include(<experimental/filesystem>)
@@ -12,17 +17,15 @@
 #else
 #error filesystem not available
 #endif
-#include "config.h"
 
-#include "selutility.hpp"
 #include "types.hpp"
 #include "utils.hpp"
 
+#include <host-ipmid/ipmid-api.h>
+
 #include <phosphor-logging/elog-errors.hpp>
 #include <xyz/openbmc_project/Common/error.hpp>
 
-#include "host-ipmid/ipmid-api.h"
-
 extern const ipmi::sensor::InvObjectIDMap invSensors;
 using namespace phosphor::logging;
 using InternalFailure =