Option to Save Downloaded APKs Without Installing Them

[rancidfrog]

Currently app forces user to use permission:

User might want just to download latest releases and install from file explorer.
Having the option to keep app usable without forcing permissions on users would be greatly appreciated

Alternatively,
Some users might just want to check if update is available.

[ImranR98]

May want to keep #44 in mind when working on this issue, as they both involve tracking Apps without APK installation (and possibly without APK download).

[ImranR98]

Adding this comment from @jeremiah-k on #1007:

One of my main uses for Obtainium is to use it for updating the Meshtastic (offline encrypted meshnets via LoRa) Android app + tracking new firmware releases (thank you for implementing the "Track Only" feature so I'm able to do that).

For this feature request, in situations where internet access is inaccessible having the latest stable apk stored locally would be invaluable for Bluetooth sharing later.

So rather than downloading & installing the apk, then deleting the cache. It would be great if we could specify a folder to store the last successfully installed version. Also if there are multiple files for different architectures we would be able to select & download those files, even if we are only installing one on our phone.

Thank you!