Expose Bound Workspace models in Execution View for each Teiid Server

To assist the user in both creating/changing and viewing workspace source-to-connector bindings, show a "workspace models" root under each Teiid Server root showing each bound model and it's current connector binding.

The reverse of this is to maintain a "connector-to-source" binding object in the Model Explorer view for each source model. (if bound)

In addition, maybe allow users to DND models and bindings in this view to change bindings on the fly.