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: Ie85ba085aedffd41bcb6310ee57adb86cb68273d
diff --git a/test/post_reporter_test.cpp b/test/post_reporter_test.cpp
index 0a13769..8f7f503 100644
--- a/test/post_reporter_test.cpp
+++ b/test/post_reporter_test.cpp
@@ -28,7 +28,7 @@
     }
 
     NiceMock<sdbusplus::SdBusMock> bus_mock;
-    sdbusplus::bus::bus bus;
+    sdbusplus::bus_t bus;
 };
 
 TEST_F(PostReporterTest, EmitsObjectsOnExpectedDbusPath)