Add option to keep main application window closed on OS restart

[kurdin]

Currently, when the user restarts their computer, the main application window automatically appears on screen. This behavior may not be desired for all users, especially those who prefer a more discreet startup process.

Feature request:

• Implement an option to keep the main application window closed when the operating system restarts, If the user closed the main app window before restart.
• This setting should persist across system reboots.

[kurdin]

Added option to user preferences

• Application starts with main window hidden

[kurdin]

New version has been released with new option to keep main application window closed on OS restart.
https://github.com/PasteBar/PasteBarApp/releases/tag/v0.6.0
#142