test: add helper function for checking for a specific event type

test: add helper function for checking for a specific event type

In a few tests we care about that a specific set of events are in the queue
but not about the details of the events (usually checked elsewhere). Instead
of manual loops, provide a helper function that also checks that there is at
least one of those events in the queue.

Signed-off-by: Peter Hutterer <peter.hutterer@who-t.net>