Update return type for getAllEvents

[shanekim28]

Updated return type of getAllEvents to utilize the GetAllEventsResponse DTO

Responds partly to #288

Held off on updating the response to cancelMerchOrder. There was a discrepancy in the behaviours of cancelMerchOrder, fulfillMerchOrderItems, and rescheduleOrderPickup. I noticed fulfillMerchOrderItems returns a FulfillMerchOrderResponse DTO and modifies the respective order, but the other two routes do not return anything despite modifying the model. Not sure if this was intended, but may be worth looking into for consistency.

[github-actions]

Thanks for contributing! If you've made changes to the API's functionality, please make sure to bump the package version—see this guide to semantic versioning for details—and document those changes as appropriate.

[shravanhariharan2]

Thanks for contribuing! Our type system for our controllers and services are currently a bit incomplete / inconsistent (e.g. missing return types for controllers, returning Public types vs. Model types in the services, to name a few), and we're looking to refactor these during our upcoming undertaking of exporting a types package. We're going to discuss these discrepancies with the rest of the development team to iron out where responses should be returned vs. where they shouldn't (i.e. figuring out where the frontend should or shouldn't be using the responses to their API calls), so you can expect that to be resolved within a few weeks.

For now, we can merge in this PR to patch the getAllEvents route, and we can handle the rest of the type discrepancies in future PRs relating to that package refactor.