JBIDE-16133: Provide better feedback for incorrect admin password

* JBoss[7]ServerUtil
* TeiidServerAdapterFactory
 * Rather than catching JBoss exceptions (may be caused by incorrect
   security credentials) throw them instead and force UI components to
   catch and process them

* TeiidServer
 * Better handle exceptions thrown when failing to connect to teiid instance

* TeiidServerEditor
* TeiidParentServerListener
 * Rather than just logging exceptions thrown when initialising the teiid
   instance, get the exception back to the user

* DqpPlugin
 * API for handling exceptions by displaying them using an ErrorDialog
 * This is not ideal given that the DqpPlugin is technically a non-UI
   plugin despite depending on org.eclipse.ui.
 * At some point, this needs refactoring to set a UI provider for displaying
   exceptions in the UI.
TEIIDDES-1944: check jboss server prior to refreshing teiid instance

* Avoids throwing an exception when refreshing a stopped teiid instance
* Displays sensible error message instead