Remove query

[smkhalsa]

per #9, this PR removes the Query widget in favor of using StreamBuilder directly. This change narrows the API without losing core functionality and allows us to remove the Flutter dependency.

QueryRequest also now implements Request from gql_exec.

[klavs]

Looks good.

As a thought experiment (and a bit of a stretch), what if there was no QueryRequest and it's config was just a class FerryContext extends ContextEntry?

• request.withContextEntry<OptimisticResponse>(...)

(I'm not saying it's necessary, or even a good idea)

With Dart extension members it could become request.withOptimisticResponse(...)

[smkhalsa]

As a thought experiment (and a bit of a stretch), what if there was no QueryRequest and it's config was just a class FerryContext extends ContextEntry?

Interesting idea!

In this case, queryController could simply be a stream of Query instead of QueryRequest<T>. I'm not sure how we'd deal with QueryRequest<T> generics since we filter by type in responseStream.

[smkhalsa]

After digging deeper on this, I'm going to hold off on removing the Query Widget for now.

Even with the equality override on QueryRequest, the StreamBuilder will constantly rebuild since calling client.responseStream(MyQuery()) will still return a unique Stream object each time.

I've thought about some workarounds, but I think it's easier just to maintain the Query widget for now.

Some of the other changes in this PR have been incorporated into #11.