#2 SQL Connection Chooser is squirrely

[Paul C Smith]

In version 2 branch, the async calls in the SQL Connection Chooser are poorly integrated. This isn't as evident of a problem in V1 because the main form in that version pre-loads the SMO results for servers.

Fix by making a self-contained, reusable SQL Connection Chooser form that handles all of its async threads internally, instead of forcing the caller to hassle with that.