`EventsService.AllAsync` needs to be corrected to return `EventListResponse` instead of `IReadOnlyList<Event>`

[IanKemp]

In #89 support for retrieving linked entities was added to the EventListResponse returned from GoCardlessClient.Events.ListAsync, but GoCardlessClient.Events.AllAsync returns IReadOnlyList<Event>, which means the latter method doesn't support linked entity retrieval. Please can this be corrected.

[iankemp-CapitalOnTap]

ListAsync return type (correct):

gocardless-dotnet/GoCardless/Services/EventService.cs

Line 47 in 97a32d1

public Task<EventListResponse> ListAsync(EventListRequest request = null, RequestSettings customiseRequestMessage = null)

AllAsync (wrong, should be IEnumerable<Task<EventListResponse>>):

gocardless-dotnet/GoCardless/Services/EventService.cs

Line 83 in 97a32d1

public IEnumerable<Task<IReadOnlyList<Event>>> AllAsync(EventListRequest request = null, RequestSettings customiseRequestMessage = null)