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:
  * exception_t
  * manager_t
  * match
  * match_rules
  * message_t
  * object_t
  * slot_t

Change-Id: I2ae68b681525ac2336ec5b2707b2dd6facb64c58
Signed-off-by: Patrick Williams <patrick@stwcx.xyz>