The media modules must run as the owner of the data they access; the data
already says who that is. Proposes ${access:<id>:uid|gid} instead of user
management in the mesh (ADR 0051).
ADR 0112 decided that an assignment places a directory and says where an
access's data is; the control plane implements neither. ace's media stack
(a 40 TB ZFS library, plex state on a second disk) cannot be expressed
without writing ace's paths into manifests.
jschoubben