lttng add-trigger: some updates to event rule to new syntax

Implement a few of the proposals for the event rule syntax related to
event names that we want to adopt for the add-trigger command.

 - Remove the positional argument (tracepoint name).
 - Add --name option for tracepoints, syscalls and loggers.
 - Add --event-name option for probes.
 - Rename --exclude to --exclude-names.
 - Remove the --all/-a option.  The equivalent now is to omit
   --name, which is the equivalent of --name=*.

Change-Id: I7161570a47716c458a60d679bc229a8c8843b04f
Signed-off-by: Simon Marchi <simon.marchi@efficios.com>
Signed-off-by: Jérémie Galarneau <jeremie.galarneau@efficios.com>