Don't force `full` (F-Droid/GitHub) releases users to grant the `All files access` permission

They may not want to give the permission, which I think is a understandable desire.

I believe that a dialog explaining why it is good to give the permission after the user has refused to grant it would be good. It should have an option to try granting the permission again and one to work the same way as `play` builds do.