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: I223d58649a21565678bd7ef78d955b30d3fd6d84
diff --git a/test/utest.cpp b/test/utest.cpp
index 9375600..2bd222b 100644
--- a/test/utest.cpp
+++ b/test/utest.cpp
@@ -11,7 +11,7 @@
 class LedTest : public ::testing::Test
 {
   public:
-    sdbusplus::bus::bus bus;
+    sdbusplus::bus_t bus;
     LedTest() : bus(sdbusplus::bus::new_default())
     {
         // Nothing here