Notify and resume of unsuccessful uploads

## Basic Info

Android 10 One UI 2.0
Galaxy S9
I'm running Cryptomator in version: 1.4.3

## Description

When a multi-file upload process is started and left in background, it may be stopped by Android due to insufficient memory. In this case the user is never notified that the process actually did not complete successfully and some files are missing.

It would be nice to have a log and see which files were successfully and unsuccessfully uploaded, as well as have the option to resume unsuccessful uploads. Otherwise it is a significant hassle to go back and count all the files manually to ensure nothing is missed.

edit: This is another issue that I am having but not sure if it warrants a formal issue on its own. Almost all upload processes that I start (~10-50 images each) in the background do not finish, even if my device has 2GB free memory at the time. When I reopen the app the vault is still accessible and unlocked and it does not seem like the app has been killed. Is this a reported issue or is it likely due to something external consistently killing the upload process specifically?