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: I6a559082fed34ae62b648345ead793436d2d03f6
diff --git a/src/propertywatch.hpp b/src/propertywatch.hpp
index 6cb1d63..7c5f468 100644
--- a/src/propertywatch.hpp
+++ b/src/propertywatch.hpp
@@ -80,7 +80,7 @@
      *  @param[in] path - The path associated with the message.
      *  @param[in] interface - The interface associated with the message.
      */
-    virtual void propertiesChanged(sdbusplus::message::message&,
+    virtual void propertiesChanged(sdbusplus::message_t&,
                                    const std::string& path,
                                    const std::string& interface) = 0;
 
@@ -91,7 +91,7 @@
      *  @param[in] msg - The org.freedesktop.DBus.PropertiesChanged
      *               message.
      */
-    virtual void interfacesAdded(sdbusplus::message::message& msg) = 0;
+    virtual void interfacesAdded(sdbusplus::message_t& msg) = 0;
 
   protected:
     /** @brief Property names and their associated storage. */
@@ -154,8 +154,7 @@
      *  @param[in] path - The path associated with the message.
      *  @param[in] interface - The interface associated with the message.
      */
-    void propertiesChanged(sdbusplus::message::message& msg,
-                           const std::string& path,
+    void propertiesChanged(sdbusplus::message_t& msg, const std::string& path,
                            const std::string& interface) override;
 
     /** @brief DBus agnostic implementation of interfacesAdded.
@@ -174,7 +173,7 @@
      *  @param[in] msg - The org.freedesktop.DBus.PropertiesChanged
      *               message.
      */
-    void interfacesAdded(sdbusplus::message::message& msg) override;
+    void interfacesAdded(sdbusplus::message_t& msg) override;
 
     /** @brief DBus agnostic implementation of interfacesAdded.
      *