When updating through the app, do not download the APK a second time if it has already been downloaded

### Issue Details

I can't pause and resume updates and even if the update finished downloading sometimes i just cancel the apk installation by accident which instead of Adguard just having the apk ready after already downloading it it just download it again, not to mention background downloading on my phone it just cant.

### Proposed solution

Make an option to download the update externally with a direct link on the browser that would be much easier it would even make reverting the update easier if anything happened

### Alternative solution

_No response_