[xenial_-_android9] sync packaging changes from main branch
requested to merge personal/peat-psuwit/xenial_-_android9_-_libpkgnamechange into ubports/xenial_-_android9
Well... when I merged !19 (merged), I forgot that there's a separated branch for Android 9 that has to be updated too. And because of binary package name change, it caused the failure of Android 9 rootfs creation.
(Insert surprised pikachu meme here)
Fix that by bringing all relevant Debian packaging changes to the xenial_-_android9 branch. Besides packaging changes, this also add a Systemd unit file. However, since we don't run Systemd in Xenial it should be fine.