add-on fails ungracefully if Seeq workbook/worksheet is not found

[monstrorivas]

The add-on fails ungracefully if an API Exception is returned by Seeq when calling the Investigate option. At the moment we are only catching AzureMLExceptions. We need to add the Seeq Exception to the try/except block in _add_on_main.py

            try:
                investigation.run()
                investigation.push_to_seeq()
            except AzureMLException as e:
                self.set_error_message(title="AzureMLException: ", message=str(e))
                self.app.model_summary.button_loading = False
                return