Print/Preview dialog box to have the option to save to PDF

[elsylambert]

Users should be able to choose the option to "Save to PDF" when Previewing the text. This feature should be easily accessible within the app's interface.

DoD:

Users can select 'Save to PDF' option from the app's menu.
The feature converts the current book into a PDF format.
Users can choose the destination folder to save the PDF.
The PDF output should maintain the formatting and layout of the original content.
The application should provide feedback (like a notification) once the PDF is successfully saved.