feat(events): introduce exists APIs for events
feat(events): introduce exists APIs for events

mnubo/smartobjects-js-client,mnubo/mnubo-js-sdk,mnubo/mnubo-js-sdk,mnubo/smartobjects-js-client,blemoine/smartobjects-js-client,mnubo/smartobjects-js-client,mnubo/smartobjects-js-client,blemoine/smartobjects-js-client