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: Ic63a70d32f4683e0bd92b625cc36c836aa8395a8
diff --git a/association_manager.cpp b/association_manager.cpp
index ade689d..1b28ace 100644
--- a/association_manager.cpp
+++ b/association_manager.cpp
@@ -15,7 +15,7 @@
 {
 namespace fs = std::filesystem;
 
-Manager::Manager(sdbusplus::bus::bus& bus, const std::string& jsonPath) :
+Manager::Manager(sdbusplus::bus_t& bus, const std::string& jsonPath) :
     _bus(bus), _jsonFile(jsonPath)
 {
     // If there aren't any conditional associations files, look for