Fix return to the program

[1qq9qq]

I'll probably sound vague, but I'll try. For example, I clicked install update. Installed it, checked the hashes. Switched to another app. Then I return to ffupdater from the list of running ones. It may have already been swapped out of memory, but I'm not sure about that. And ffupdater starts downloading the same update again. Perhaps it would be better if at that moment he showed a notification that this update has already been installed, or returned to the main screen of the program.

[Tobi823]

Note for me: Move download logic in a new WorkManager job. Use DownloadActivity to query + display current progress + use setExpedited

[mh-tp]

i think you described it quite well. I'd upvote this.