TEIIDDES-2118: Display error message when jdbc connection fails

* ExecuteVdbWorker
 * Display the error dialog if the code of the connection's returned status
   is ERROR.

* TeiidJDBCConnection
 * Breaks up the exception handling to differentiate between a
   ClassNotFoundException which should be ignored and an actual connection
   failure which needs to be thrown and reported to the user
TEIIDDES-2124: Incorrect exception being caught

* Seems that ClassNotFoundException gets thrown in the IDE but a
  NoClassDefError is thrown by installs.

* Catches any throwable and discards since the important thing is whether
  jdbcDriver has been successfully assigned. If not then moves on to
  alternative initialising process.