Add success and error message dialogs, and implement threading for save changes

[duyle1402]

Hi Thiago,

Thank you for creating awesome things. When I use OpenPLC Editor to program with my ESP32 board, I noticed that when I press the "Save Changes" and "Restore Default" buttons, I don't know if the actions worked or not. To improve user experience and provide clear feedback, I have added the following enhancements:

1.Success and Error Message Dialogs:

• Added showSuccessMessage and showErrorMessage methods to display a message dialog indicating whether the operation was successful or if there was an error.
• These dialogs provide immediate feedback to the user, ensuring they know the result of their actions.

2.Threading for Save Changes:

• Implemented threading in the onSaveChange method to handle the save operation in a separate thread.
• This prevents the GUI from freezing and allows the button to be re-enabled after the save operation is complete.

These changes enhance the usability of the application by providing clear and immediate feedback to users. You can accept this pull request or not, or you can consider an alternative implementation in the future.