Refactor the public API

[rach-id]

          the api increase isn't that big of deal since its just the orchestrator/relayer, and might require a larger PR to fix properly. This is just something that was sticking was all. Ideally I think it would be great to isolate the actual queries made to the app in the app querier, and then refactor and separate the logic for getting the last, earliest, before nonce / after nonce

it would be nice to be consistent with last and earliest like we are doing in the app, as I often get confused since I'm not 100% sure we're using latest consistently. I could also just not be understanding latest.

Originally posted by @evan-forbes in #571 (review)