Back up the UI settings

[northis]

The UI settins from C:\Users\<username>\AppData\Local\Adguard_Software_Ltd\Adguard.exe_StrongName_<hash>\<version>\user.config can be deleted of corrupted. This can lead to unexpected UI settings reset. We can handle such situations by backing up the settings and restoring them instead applying the default UI settings (theme, window size etc.)