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: Ib15ce49ac136da396084ab09972dd132f02beeea
diff --git a/snmp_main.cpp b/snmp_main.cpp
index be4bea1..29c18c3 100644
--- a/snmp_main.cpp
+++ b/snmp_main.cpp
@@ -38,7 +38,7 @@
     bus.attach_event(eventPtr.get(), SD_EVENT_PRIORITY_NORMAL);
 
     // Add sdbusplus Object Manager for the 'root' path of the snmp.
-    sdbusplus::server::manager::manager objManager(bus, OBJ_NETWORK_SNMP);
+    sdbusplus::server::manager_t objManager(bus, OBJ_NETWORK_SNMP);
     bus.request_name(BUSNAME_NETWORK_SNMP);
 
     auto manager = std::make_unique<phosphor::network::snmp::ConfManager>(