sdbusplus: use shorter type aliases

The sdbusplus headers provide shortened aliases for many types.
Switch to using them to provide better code clarity and shorter
lines.  Possible replacements are for:
  * bus_t
  * exception_t
  * manager_t
  * match_t
  * message_t
  * object_t
  * slot_t

Signed-off-by: Patrick Williams <patrick@stwcx.xyz>
Change-Id: I768b8efcac262ef07cf75f06486c6144c090e91a
diff --git a/dbus.hpp b/dbus.hpp
index a8b16d8..3091fbf 100644
--- a/dbus.hpp
+++ b/dbus.hpp
@@ -46,7 +46,7 @@
  * @return ObjectValueTree - A map of object paths to their
  *                           interfaces and properties.
  */
-ObjectValueTree getManagedObjects(sdbusplus::bus::bus& bus,
+ObjectValueTree getManagedObjects(sdbusplus::bus_t& bus,
                                   const std::string& service,
                                   const std::string& objPath);
 
@@ -62,7 +62,7 @@
  * @return DbusSubtree - A map of object paths to their
  *                       services and interfaces.
  */
-DbusSubtree getSubtree(sdbusplus::bus::bus& bus, const std::string& root,
+DbusSubtree getSubtree(sdbusplus::bus_t& bus, const std::string& root,
                        int depth, const std::string& interface);
 
 /**
@@ -93,7 +93,7 @@
  *
  * @return DbusPropertyMap - The map of property names to values
  */
-DbusPropertyMap getAllProperties(sdbusplus::bus::bus& bus,
+DbusPropertyMap getAllProperties(sdbusplus::bus_t& bus,
                                  const std::string& service,
                                  const std::string& objPath,
                                  const std::string& interface);