Adds the two dormant service files for the driver-manager
post-switchroot + initfs spawner paths. Both files are dormant by
default — they require /etc/driver-manager.d/{disabled,initfs-active}
to be absent before they activate. The cutover (C1-C4) is
operator-ratified; this commit only adds the file presence so
the C0 wiring exists.
Refs: local/docs/DRIVER-MANAGER-MIGRATION-PLAN.md § 5.2 C0.
Red Bear OS
0407d9ccbb