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

Change-Id: Ie3b9c52f1fe18c89432ee7eb5d8023e028565541
Signed-off-by: Patrick Williams <patrick@stwcx.xyz>
diff --git a/test/handler_unittest.cpp b/test/handler_unittest.cpp
index a95d1df..9656364 100644
--- a/test/handler_unittest.cpp
+++ b/test/handler_unittest.cpp
@@ -146,7 +146,7 @@
     }
 
   protected:
-    sdbusplus::bus::bus getDbus() const override
+    sdbusplus::bus_t getDbus() const override
     {
         return sdbusplus::get_mocked_new(
             const_cast<sdbusplus::SdBusMock*>(mock_));