Rework types to better support getting *full* dispatch type

[EskiMojo14]

Breaking changes:

• Change ThunkAction signature from ThunkAction<ReturnType, State, ExtraThunkArg, BasicAction> to ThunkAction<Dispatch, State, ExtraThunkArg, ReturnType>
• Remove action overload and union overload from middleware type
  • Dispatch must explicitly be cast to ThunkDispatch for union to be supported
• Rework type signature for thunk overload to use this to infer Dispatch type
  • this allows other overloads to be accounted for automatically