Multi database async lookup to return a future of a map instead of a map with future values

[gedl]

Currently the async multi db look ups return Map<DatabaseProvider, CompletionStage<Optional<IpInformation>>>.

This puts a burden on the caller to deal with multiple futures.

Alternatively, a `CompletionStage<Map<DatabaseProvider,Optional>>' (or a dice-where representation of that structure), should be returned.