add middlewareBuilder notation with type-curried arguments to co…

[phryneas]

This adds the option to pass a function instead of the middleware array as middleware option on configureStore.

This function receives a middlewareBuilderApi argument of the shape

type MiddlewareBuilderApi<S> = {
  defaultMiddleware: ThunkMiddlewareFor<S>[]
  getDefaultMiddleware: CurriedGetDefaultMiddleware<S>
}

Essentially that state-type-currying allows to do something like

const store = configureStore({
      reducer: reducerA,
      middleware: ({ getDefaultMiddleware }) =>
        [
          otherMiddleware,
          ...getDefaultMiddleware({ thunk: false })
        ] as const
    })

which would before have been

const store = configureStore({
      reducer: reducerA,
      middleware: [
          otherMiddleware,
          ...getDefaultMiddleware<RootState, { thunk: false }>({ thunk: false })
        ] as const
    })

Also, it is now not necessary to know the RootState type, which makes the use of custom middlewares possible in combination with the object-type reducer notation in TS.

(Also, while touching those files anyway, I moved the separated "3.4 tests" back into normal test suite, as we're not supporting pre-3.4 TS any more)

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[markerikson]

What's the reasoning for passing in both getDefaultMiddleware and middleware?

[phryneas]

I figured it might be the most common use case to just use the default middleware and extend it like

middleware: ({defaultMiddleware}) => [ ...defaultMiddleware, logger ], but that some people also might want to change the options, so I added both.

But we can go the "only getDefaultMiddleware" (that one is definitely required while the other is more convenience) route as well.

[markerikson]

Yeah, I get the thought of just handing them the array, but let's assume that if they're providing a callback here that they're probably going to want to customize something, or at least that it's not too much work to have them call it here.

[phryneas]

Okay, I cut it down to just the curriedGetDefaultMiddleware.