selftests/ftrace: Add test that tests event :mod: commands

selftests/ftrace: Add test that tests event :mod: commands

Now that here's a :mod: command that can be sent into set_event, add a
test that tests its use. Both setting events for a loaded module, as well
as caching what events to set for a module that is not loaded yet.

Cc: Shuah Khan <shuah@kernel.org>
Cc: Masami Hiramatsu <mhiramat@kernel.org>
Cc: Mark Rutland <mark.rutland@arm.com>
Cc: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: linux-kselftest@vger.kernel.org
Link: https://lore.kernel.org/20250116143533.819228058@goodmis.org
Signed-off-by: Steven Rostedt (Google) <rostedt@goodmis.org>