trigger: consider name in trigger _is_equal()`

trigger: consider name in trigger _is_equal()`

For the moment, this is a breaking change since, before 2.13, users
could not register two identical triggers.

Triggers were previously unnamed, but a name is now generated
automatically. This means that a pre-2.13 user that could expect
a TRIGGER_ALREADY_EXISTS reply when registering a trigger that already
existed will now get "OK".

However, since it doesn't know about trigger names, it could now fail
to unregister a trigger (if the instance used to register the trigger
was not kept around).

Signed-off-by: Francis Deslauriers <francis.deslauriers@efficios.com>
Signed-off-by: Jérémie Galarneau <jeremie.galarneau@efficios.com>
Change-Id: I9549980677e2387a7cc0f275233a3b5717fb915e