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: I9cedddf4dc9b224ecbc2f68e6b00c0ab1885a826
diff --git a/settings.hpp b/settings.hpp
index 61eba03..5042c9e 100644
--- a/settings.hpp
+++ b/settings.hpp
@@ -25,7 +25,7 @@
      * @param[in] bus - The D-bus bus object
      */
     Objects() = delete;
-    explicit Objects(sdbusplus::bus::bus&);
+    explicit Objects(sdbusplus::bus_t&);
     Objects(const Objects&) = delete;
     Objects& operator=(const Objects&) = delete;
     Objects(Objects&&) = default;
@@ -47,7 +47,7 @@
     Path timeSyncMethod;
 
   private:
-    sdbusplus::bus::bus& bus;
+    sdbusplus::bus_t& bus;
 };
 
 } // namespace settings