Change default user uid to 10000
This PR changes default user UID in pmOS installation to 10000 instead of 1000 to avoid conflicts with Android userspace, which is useful when running Android services in container for libhybris and is needed for PR #1522. This is resubmit of #1576.
This breaks existing chroots and will require them to be zapped and recreated, or UI won't autostart on device, which is now handled in pmb.helpers.other.migrate_work_folder().