server: minor refactoring

Move files into a server subdirectory to correspond to the 'server'
namespace and create a 'server.hpp' as method to gain includes
needed by any server instance.  Create a few type aliases to
reduce namespace levels.

Change-Id: I8f8ea8e57177393faa007351a540d08873d36632
Signed-off-by: Patrick Williams <patrick@stwcx.xyz>
diff --git a/tools/templates/interface.mako.server.hpp b/tools/templates/interface.mako.server.hpp
index fa499b4..1d23646 100644
--- a/tools/templates/interface.mako.server.hpp
+++ b/tools/templates/interface.mako.server.hpp
@@ -1,9 +1,7 @@
 #pragma once
 #include <tuple>
 #include <systemd/sd-bus.h>
-#include <sdbusplus/vtable.hpp>
-#include <sdbusplus/interface.hpp>
-#include <sdbusplus/bus.hpp>
+#include <sdbusplus/server.hpp>
     <%
         namespaces = interface.name.split('.')
         classname = namespaces.pop()
@@ -51,7 +49,7 @@
     % endfor
 
         static constexpr auto _interface = "${interface.name}";
-        static const sdbusplus::vtable::vtable_t _vtable[];
+        static const vtable::vtable_t _vtable[];
         interface::interface _${"_".join(interface.name.split('.'))}_interface;
 
 };