Description
For most users of beeline, chances are that they will be using it with a single HS2 instance most of the time. In this scenario, having them type out a jdbc uri for HS2 every single time to !connect can get tiresome. Thus, we should improve semantics so that if a user does a successful !connect, then we must store the last-connected-to-url, so that if they do a !close, and then a !reconnect, then !reconnect should attempt to connect to the last successfully used url.
Also, if they then do a !save, then that last-successfully-used url must be saved, so that in subsequent sessions, they can simply do !reconnect rather than specifying a url for !connect.
In addition, it would be useful to introduce a new way of doing !connect that does involve typing out a jdbc url every time (since this is highly likely to be error-prone)