fix include names

cppcheck isn't smart enough to recognize these are c++ headers, not c
headers.  Considering we're already inconsistent about our naming, it's
easier to just be consistent, and move the last few files to use .hpp
instead of .h.

Tested:
Code builds, no changes.

Signed-off-by: Ed Tanous <ed@tanous.net>
Change-Id: Ic348d695f8527fa4a0ded53f433e1558c319db40
diff --git a/include/dbus_monitor.hpp b/include/dbus_monitor.hpp
index 089df76..aeab103 100644
--- a/include/dbus_monitor.hpp
+++ b/include/dbus_monitor.hpp
@@ -1,7 +1,5 @@
 #pragma once
-#include <app.h>
-#include <websocket.h>
-
+#include <app.hpp>
 #include <async_resp.hpp>
 #include <boost/container/flat_map.hpp>
 #include <boost/container/flat_set.hpp>
@@ -9,6 +7,7 @@
 #include <openbmc_dbus_rest.hpp>
 #include <sdbusplus/bus/match.hpp>
 #include <sdbusplus/message/types.hpp>
+#include <websocket.hpp>
 
 #include <variant>