Issue #2975334 by amateescu, Wim Leers, plach, effulgentsia, webchick, timmillwood, yoroy: Prevent changes that would leak into the Live workspace

(cherry picked from commit 4ea4c13f)

Issue #2958752 by amateescu, timmillwood, catch: Refactor workspace content replication plugin system to three services

Issue #2784921 by amateescu, timmillwood, pk188, plach, catch, Fabianx, dixon_, dawehner, borisson_, Sam152, yoroy, webchick, phenaproxima, larowlan: Add Workspaces experimental module