Android: Downloads are confusing

Downloading files in Tor Browser on Android is sometimes confusing and not safe. There are two separate but related issues.

Problems:

1. Downloads are saved in the shared storage. See legacy/trac#26574 (moved) for more information about this and downloading files into the app's internal storage.
2. When the app is restarted after downloading a file, the file is not listed in Tor Browser's Downloads list anymore. This is very confusing, especially because the file is still saved in the shared storage. I suspect this is because private browsing mode doesn't save state (including recent downloads).