DRILL-6591: Show Exception for failed queries submitted in WebUI
* DRILL-6591: Show Exception for failed queries submitted in WebUI
When query fails on Web UI result page no error is shown, only "No result found."
This was because DRILL-6477 (PR #1309) switched to `WebUserConnection.await(long timeoutInMillis)` . Unlike the original `WebUserConnection.await()`, this method did not throw any UserException generated by a query failure. The fix was to use WebUserConnection.getError() method to know about failure of the query and throw UserRemoteException with that.
closes #1379
