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: Ibc25db433a6926f7ee43ea83312c3ac14f480c33
diff --git a/test/extensions_test.cpp b/test/extensions_test.cpp
index a3bd119..c54f376 100644
--- a/test/extensions_test.cpp
+++ b/test/extensions_test.cpp
@@ -60,7 +60,7 @@
 TEST(ExtensionsTest, FunctionCallTest)
 {
     sdbusplus::SdBusMock sdbusMock;
-    sdbusplus::bus::bus bus = sdbusplus::get_mocked_new(&sdbusMock);
+    sdbusplus::bus_t bus = sdbusplus::get_mocked_new(&sdbusMock);
     internal::Manager manager(bus, "testpath");
 
     EXPECT_EQ(Extensions::getStartupFunctions().size(), 2);