This injects FileSelectionManager as a singleton, so we can use its selection to recreate a snapshot, even in a service.
Also includes some UI improvements.
and allow changing them dynamically. So far plugins were injected into the dependency graph and couldn't be changed at runtime, only their config could. Now we have the infrastructure in place to really allow for more than one plugin.
We use the same root folder for app and files backup. App backup usually creates the root folder, but if only storage backup is used, it will be missing and needs to be created.
By default, Android exposes USB devices only to the main user.
In order to query, read and write to it, the signature permission INTERACT_ACROSS_USERS_FULL (optional) is granted to create Seedvault's context as the system user.
Issue: calyxos#437
Issue: https://github.com/seedvault-app/seedvault/issues/77
Change-Id: I0b1b4c8c5aeeb226419ff94e15f631ebe1db66df
Previously, we would put our files directly in the root of the storage location and delete any existing backups there. When used by different devices or user profiles, these would keep deleting each other's backups.
