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Fix T78071: Drivers reading object visibility not updating automatically

An object can be targeted by a driver that reads its `hide_viewport` or
`hide_render` property. The existence of such a driver will create a
relation between the 'sync base flags' depsgrpah node, and the datablock
containing the driver. When the object is hidden, however, it has no
base, and thus it had no 'sync base flags' depsgraph node. To support
such a driver, that depsgraph node is now always added, but for hidden
objects it will just be a no-op. If the node is not used by anything, it
will be automatically disconnected and have a negligible effect on
performance.