Fix a crash when a driver variable targets an object and uses
`data.shape_keys.key["name"].value` in its expression.
The fix consists of adding an extra relation from the targeted object's
`GEOMETRY` component to the driver evaluation. This ensures that its
`data` pointer has been evaluated by the depsgraph and is safe to
follow.
This also resolves the concern raised on rB56407432a6aa.
Reviewed by: brecht
Differential Revision: https://developer.blender.org/D14956
a2dacefb46