Add test helper function to create STAN connection with NATS opts
Add test helper function to create STAN connection with NATS opts

In some tests, we want to speed up the reconnect from the client.
We had to create a NATS connection with appropriate ReconnectWait
option, then pass this to the stan.Connect() call. Made that an
helper function.

petemiron/nats-streaming-server,petemiron/nats-streaming-server,petemiron/nats-streaming-server,nats-io/nats-streaming-server,nats-io/nats-streaming-server