Allow manually downgrading the app

### Issue Details

When a user tries to install a build with a lower version number than the currently installed one, the installer displays the message “AdGuard VPN is already installed.” This safeguard exists to avoid migration-related issues.

Currently, the only way to override this behavior is to run the installer from PowerShell using the `/F` key.

### Proposed solution

Allow downgrading by manually running the installer without requiring a special key. Any potential migration issues should be handled by resetting the application settings to their default values during the downgrade process or on first launch.

### Additional info

Awating for upwotes