Use RPC service object from NetworkController

[mcmire]

As a part of the RPC failover project, we are adding an RpcService class to @metamask/network-controller. This class will not only implement the retry and circuit breaker patterns but will also include the same logic as in this package and @metamask/eth-json-rpc-middleware to retry specific connectivity and response errors.

With this ticket, we will be able to also knock out #77.