Install in /system/priv-app

DownloadProviderUi app is privileged because it runs in the
same user (and same process) as other priv-apps such as the
MediaProvider and gains all the privileges of that user. Mark
it appropriately so that PackageManager scans it correctly.

Bug: 71593002
Test: Build and flash Taimen. Verify that DownloadProviderUi is
    installed in /system/priv-app instead of /system/app.

Change-Id: Ic3b45c7d38a49f6486f628429a24dd59f50a1cef
2 files changed