expose query props via a RemoteData(-like?) API

[giogonzo]

requirements

each "query prop" is currently exposed by declareQueries to the component as follows
https://github.com/buildo/react-avenger/blob/master/src/index.d.ts#L14-L25 which is roughly:

{
  queryProps: {
    ready: false,
    loading: boolean
  } | {
    ready: true,
    value: T,
    loading: boolean
  }
}

This is not the best to work with in common component scenarios, for various reasons among which:

• it doesn't incentivate the explicit handling of all possible cases (loading, success and, sometimes, success+loading)
• it requires a lot of if / conditional checks that can't be chained nor easily used to make a function exhaustive

specs (DRAFT with doubts)

RemoteData https://github.com/devex-web-frontend/remote-data-ts exposes an ADT made of the possible cases: NotAsked | Pending | Failure | Success

Re NotAsked

It's never needed by us (rendering a component means having requested some piece of data). We could re-define our own RemoteData type based on the original, by removing this case. The fold() method would have just 3 cases instead of 4.
An alternative could be to keep using the same method but export a utility function similar to fold
that combines NotAsked and Pending in the same case, effectively ignoring the "inexistent" NotAsked case.

do we want to treat all declared queries in the same way?

e.g. sometimes you want to render if the required data are there, and the re-render with additional data later.
This is already ok, since we have a per-query prop and we can combine multiple props
in render if e.g. two out of three are required:
sequenceT(remoteData)(query1, query2 /* but not query3 */).fold()

Sometimes we want to render a success + loading state

(when we are re-fetching some data that we already have)
RemoteData doesn't handle this case out of the box.
What we might do: declareQueries defaults to the most common case (data | loading | success)
but one may configure it to get a fold() method comprising 4 cases instead of 3?

misc

{optional: other useful info}