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: I1c3acea60ea58b8a0f9a76fd32b5d0d007bf1a16
diff --git a/fail-monitor/monitor.hpp b/fail-monitor/monitor.hpp
index a8a387f..9c98fdf 100644
--- a/fail-monitor/monitor.hpp
+++ b/fail-monitor/monitor.hpp
@@ -83,7 +83,7 @@
     /**
      * The dbus object
      */
-    sdbusplus::bus::bus bus;
+    sdbusplus::bus_t bus;
 
     /**
      * The source unit