tests/qtest: migration events

Define a state object to capture events seen by migration tests, to allow
more events to be captured in a subsequent patch, and simplify event
checking in wait_for_migration_pass.  No functional change.

Signed-off-by: Steve Sistare <steven.sistare@oracle.com>
Reviewed-by: Fabiano Rosas <farosas@suse.de>
Reviewed-by: "Daniel P. Berrangé" <berrange@redhat.com>
Link: https://lore.kernel.org/r/1704312341-66640-10-git-send-email-steven.sistare@oracle.com
Signed-off-by: Peter Xu <peterx@redhat.com>
3 files changed