ir: trace: pass remove listeners when adding listeners

With this patch, when you call bt_ctf_trace_add_is_static_listener(),
you can also provide a "remove listener" which is called when the added
listener is removed, weither manually with
bt_ctf_trace_remove_is_static_listener(), or when the trace object is
destroyed. This is useful when you dynamically allocate data only for
the listener to add and you are not the only owner of the trace object:
the remove listener is where to free/release this data.

Existing plugins and tests are modified to match and test this change.

Signed-off-by: Philippe Proulx <eeppeliteloop@gmail.com>
Signed-off-by: Jérémie Galarneau <jeremie.galarneau@efficios.com>