[Enhancement] Prevent iOS auto-lock while VM is running

[conath]

Currently while a VM is running, the iOS device will eventually auto-lock and cause the VM to suspend. In my opinion this should be prevented, the API for this is UIApplication.isIdleTimerDisabled.

    // Disable iOS auto-lock
    UIApplication.shared.isIdleTimerDisabled = false;

Naturally, leaving the screen on and the VM running indefinitely will drain the device's battery. Therefore it might be reasonable to include a setting that controls this behavior (in the Settings bundle?).