External tools state and additional information should be saved on the validation end

One can start external tools validation and close application settings dialog. In this case tools will be validated and their state will be set in UGENE, but it won't be saved in the settings file.
Next things have to be done:

1. External tools validation data have to be saved on validation complete, if the application settings dialog was already accepted.
2. External tools validation data mustn't be saved on validation complete, if the application settings dialog was canceled, even if the validation task is finished.
3. Validation tasks should be canceled if application settings dialog was cancelled.