Add autostart support on settings

[scardracs]

Description

This PR implements the Autostart feature for rog-control-center. It allows users to configure the application to run automatically on system boot, with the option to launch it minimized to the system tray/background.

Core Features:

• System Autostart Integration: Creates and manages the user's autostart desktop entry file (~/.config/autostart/rog-control-center.desktop) automatically.
• Autostart Customization (UI Closed / Background Startup): Provides settings to choose whether the application starts minimized to the background on system startup.
• Autostart Status Sync: Dynamically synchronizes the autostart state on application startup to ensure configuration consistency.
• UI Controls: Integrates user toggles inside the App Settings page to easily enable/disable system autostart and configure its startup state.

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Technical Details

• rog-control-center/src/config.rs:
  • Added enable_autostart and autostart_in_background to the core configuration struct.
  • Implemented update_autostart to write/remove the rog-control-center.desktop entry in ~/.config/autostart/ with correct launch arguments (--background).
  • Added unit test coverage for the autostart desktop file creation.
• rog-control-center/src/cli_options.rs: Added the --background argument flag to support starting minimized.
• rog-control-center/src/main.rs: Added startup initialization to keep the autostart entry in sync and parsed the --background CLI flag to run the application in the background when autostarted.
• rog-control-center/ui/pages/app_settings.slint: Added the "Start app on system startup" toggle and the nested "Start in background on startup" sub-option.
• rog-control-center/src/ui/mod.rs: Registered state bindings and callbacks to handle autostart events from the GUI.

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End Result