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: Ic68a12ef7c12222b1300981282161c971b561dc1
diff --git a/sessions_manager.hpp b/sessions_manager.hpp
index cd7f016..512b17c 100644
--- a/sessions_manager.hpp
+++ b/sessions_manager.hpp
@@ -158,7 +158,7 @@
      *        associative container with Session ID as the unique key
      */
     SessionMap sessionsMap;
-    std::unique_ptr<sdbusplus::server::manager::manager> objManager = nullptr;
+    std::unique_ptr<sdbusplus::server::manager_t> objManager = nullptr;
     std::string chName{}; // Channel Name
     uint8_t ipmiNetworkInstance = 0;
     void setNetworkInstance(void);